Opinion by Judge GOULD; Dissent by Judge GRABER.
GOULD, Circuit Judge:Winston Davenport appeals the district court’s denial of Davenport’s motion to withdraw his guilty plea and the sentence that the district court imposed on him for one count of receiving child pornography in violation of 18 U.S.C. § 2252A(a)(2) and one count of possessing child pornography in violation of 18 U.S.C. § 2252A(a)(5)(B). After the district court denied Davenport’s motion to withdraw his guilty plea, Davenport received a 78-month sentence of incarceration for each of the two counts, to be served concurrently, as well as concurrent life terms of supervised release for each count.
In this opinion we address whether Davenport’s conviction for both 18 U.S.C. § 2252A(a)(2), or receipt of child pornography, and 18 U.S.C. § 2252A(a)(5)(B), or possession of child pornography, offends double jeopardy when the conduct underlying both offenses is the same.1 We have jurisdiction pursuant to 28 U.S.C. § 1291, and we determine that Davenport’s simultaneous conviction for both receipt and possession of child pornography violates the Fifth Amendment’s prohibition on double jeopardy. We reverse and remand to the district court for further proceedings consistent with this opinion.
I
In September of 2005, the Helena, Montana office of the Department of Homeland Security, Immigration and Customs Enforcement (“ICE”) learned that an IP address associated with Davenport had been used to access a file-sharing program and download images of child pornography from other computer users. The ICE investigated Davenport’s involvement with child pornography, and forensic analysis of Davenport’s computer revealed 496 images and 334 videos containing child pornography, child erotica, or other possible images of interest. Some of these materials depicted violence or involved children under the age of twelve.
Davenport was indicted by a grand jury on February 16, 2006 on one count of receiving child pornography in violation of 18 U.S.C. § 2252A(a)(2), one count of possessing child pornography in violation of 18 U.S.C. § 2252A(a)(5)(B), and one count of forfeiture under 18 U.S.C. § 2253(a) which requires defendants convicted of child pornography offenses to relinquish all rights to the computer on which the pornography was found. Davenport entered into a plea agreement with the government on April 21, 2006, waiving his right to appeal issues regarding his conviction but not his sentence, in exchange for a promise that the government would recommend a sentence of either the mandatory statutory minimum or the bottom of the Guidelines range, whichever was higher. A change of plea hearing was held on April 24, 2006, at which Davenport stated under oath, among other things, that he was guilty of each of the elements of both receipt and possession of child pornography.
At a sentencing hearing held on October 25, 2006, Davenport received 78 months of incarceration for the receipt and posses.sion counts, each, with the two sentences to be served concurrently, followed by two concurrent lifetime terms of supervised release. The judgment recording this con*943viction and sentence'was entered on October 27, 2006. Davenport now argues, for the first time on appeal, that his sentence for both receipt and possession of child pornography is impermissible because the two convictions, based on the same conduct, are multiplicitous, in violation of the Fifth Amendment’s Double Jeopardy Clause.
II
Although we normally review de novo claims of double jeopardy violations, United States v. Jose, 425 F.3d 1237, 1240 (9th Cir.2005), we review issues, such as the present one, not properly raised before the district court for plain error. See Fed. R.Crim.P. 52(b); United States v. Olano, 507 U.S. 725, 730-36, 113 S.Ct. 1770, 123 L.Ed.2d 508 (1993); United States v. Valenzuela, 495 F.3d 1127, 1130 (9th Cir. 2007). Under the plain error standard, we will affirm Davenport’s sentence unless: (1) there has been an error in the proceedings below; (2) that error was plain; (3) it affected substantial rights; and (4) it seriously affected the fairness, integrity, or public reputation of judicial proceedings. Olano, 507 U.S. at 733, 113 S.Ct. 1770; Valenzuela, 495 F.3d at 1130.
III
The Fifth Amendment’s prohibition on double jeopardy protects against being punished twice for a single criminal offense. U.S. Const. amend. V.; Brown v. Ohio, 432 U.S. 161, 165, 97 S.Ct. 2221, 53 L.Ed.2d 187 (1977). When multiple sentences are imposed in the same trial, “the role of the constitutional guarantee is limited to assuring that the court does not exceed its legislative authorization by imposing multiple punishments for the same offense.” Brown, 432 U.S. at 165, 97 S.Ct. 2221. Wdien a defendant has violated two different criminal statutes, the double jeopardy prohibition is implicated when both statutes prohibit the same offense or when one offense is a lesser included offense of the other. Rutledge v. United States, 517 U.S. 292, 297, 116 S.Ct. 1241, 134 L.Ed.2d 419 (1996). To determine whether two statutory provisions prohibit the same offense, we must examine each provision to determine if it “requires proof of a[n'additional] fact which the other does not.” Blockburger v. United States, 284 U.S. 299, 304, 52 S.Ct. 180, 76 L.Ed. 306 (1932); Ball v. United States, 470 U.S. 856, 861, 105 S.Ct. 1668, 84 L.Ed.2d 740 (1985); United States v. Williams, 291 F.3d 1180, 1186-87 (9th Cir.2002), overruled on other grounds by United States v. Gonzales, 506 F.3d 940 (9th Cir.2007) (en banc). We also employ this analysis, commonly known as the Blockburger test, to determine whether one offense is a lesser included offense of another. Rutledge, 517 U.S. at 297, 116 S.Ct. 1241. If two different criminal statutory provisions indeed punish the same offense or one is a lesser included offense of the other, then conviction under both is presumed to violate congressional intent. See Missouri v. Hunter, 459 U.S. 359, 366-67, 103 S.Ct. 673, 74 L.Ed.2d 535 (1983).
Davenport advances this basic proposition that we have adopted in other statutory contexts: It is impossible to ‘receive’ something without, at least at the very instant of ‘receipt,’ also ‘possessing’ it. As we have recognized elsewhere, “federal statutes criminalizing the receipt of contraband [generally] require a knowing acceptance or taking ... possession of the prohibited item.” United States v. Romm, 455 F.3d 990, 1001 (9th Cir.2006) (internal quotation marks omitted); see also United States v. Mohrbacher, 182 F.3d 1041, 1048 (9th Cir.1999) (looking to the relevant statute’s plain language and adopting, for statutory interpretation purposes, the ordinary meaning of the word, “receive,” .namely “to take ... into one’s possession”).
*944From this, Davenport urges us to conclude that the offenses described in 18 U.S.C. § 2252A(a)(2) also cover the offenses described in 18 U.S.C. § 2252A(a)(5)(B), so that possession is a lesser included offense of receipt. Davenport asserts that, while the government may have been within constitutional boundaries to include both offenses in the indictment, and could permissibly have continued to prosecute Davenport for both offenses through trial, see Ball, 470 U.S. at 865, 105 S.Ct. 1668, entering judgment against him on these counts was multiplicitous and therefore in violation of the Fifth Amendment’s prohibition of double jeopardy. We agree.
We begin by comparing the text of each provision. See Williams, 291 F.3d at 1187 (citing Carter v. United States, 530 U.S. 255, 260-61, 120 S.Ct. 2159, 147 L.Ed.2d 203 (2000)) (“The Supreme Court has recognized that comparing statutes to determine whether one set of elements is a subset of another requires a purely textual comparison.”). 18 U.S.C. § 2252A(a)(2), the “Any person who ... knowingly receives or distributes ... any child pornography that has been mailed, or shipped or transported in interstate or foreign commerce by any means, including by computer ...” 18 U.S.C. § 2252A(a)(5)(B), the “possession” provision, criminalizes the “knowing[ ] possession of] any book, magazine, periodical, film, videotape, computer disk, or any other material that contains an image of child pornography that has been mailed, or shipped or transported in interstate or foreign commerce by any means, including by computer, or that was produced using materials that have been mailed, or shipped or transported in interstate or foreign commerce by any means, including by computer.... ”
The government contends that the receipt and possession provisions are not multiplicitous because each provision requires proof of an element that the other does not. First, it asserts that the receipt provision, 18 U.S.C. § 2252A(a)(2), requires that the pornographic material be “shipped or transported in interstate ... commerce by any means, including by computer,” while in 18 U.S.C. § 2252A(a)(5) the pornography need only be “produced using materials that have been ... shipped or transported in interstate ... commerce.” Thus, the government argues, entirely homemade child pornography may support a conviction for violating the possession but not the receipt provision. Second, the government contends that the affirmative defense in 18 U.S.C. § 2252A(d), applicable to 18 U.S.C. § 2252A(a)(5) but not to 18 U.S.C. § 2252A(a)(2), constitutes “proof of a[n additional] fact,” under the Blockburger test, required for possession but not for receipt. We consider and reject the government’s Blockburger analysis.
In so far as the interstate commerce nexus is concerned, we discern no difference between the positions advocated by the government and Davenport, respectively. Both parties recognize that the interstate commerce requirement is technically different for receipt and possession. Moreover, both parties recognize that the receipt provision necessarily requires shipment of the pornography, while the possession provision may meet the interstate commerce nexus either by shipment or by alternative means.2 Indeed, by meeting the interstate commerce nexus required for receipt, one necessarily also sustains the required possession nexus: under 18 U.S.C. § 2252A(a)(5)(B), the child pornography may itself have “been mailed, or *945shipped or transported in interstate or foreign commerce by any means ... or ... produced using materials that have been mailed, or shipped or transported in interstate or foreign commerce by any means.” Id. (emphasis added). Because possession’s nexus requirement can be met in one of two ways and receipt’s nexus requirement is one of those two ways, then at least as to the interstate commerce nexus, a conviction for receipt necessarily includes proof of the elements required for conviction under possession, and possession is a lesser included offense of receipt.
In contrast, the government’s argument fails when it attempts to show that the crime of possession requires proof of an element that the crime of receipt does not. The failure inheres in the government’s resort to the affirmative defenses in Section 2252(d). To explain why, we first revisit the Blockburger test, which commands us to examine each provision to determine if it “requires proof of a[n additional] fact which the other does not.” Blockburger, 284 U.S. at 304, 52 S.Ct. 180 (emphasis added). The government’s argument overlooks the nature of affirmative defenses generally, and in particular of the type found in 18 U.S.C. § 2252A(d). Affirmative defenses are complete defenses that, once proven by the defendant, negate criminal liability for an offense, notwithstanding the government’s ability otherwise to prove all elements of that offense beyond a reasonable doubt. The most significant difference, for purposes of our Blockburger analysis, between the elements of 18 U.S.C. § 2252A(a)(2) and (a)(5) and the affirmative defense found in 18 U.S.C. § 2252A(d) is that, unless a defendant asserts that affirmative defense; the government need not negate it to obtain a conviction. Accordingly, the factual prerequisites of 18 U.S.C. § 2252A(d)— namely, that the defendant possessed fewer than three images of child pornography and, among other things, promptly either took reasonable steps to destroy each image or reported the matter to law enforcement — are not facts that require proof under Blockburger at all. See, e.g., Patterson v. New York, 432 U.S. 197, 206-07, 209-10, 97 S.Ct. 2319, 53 L.Ed.2d 281 (1977) (holding that the federal constitution does not require proof of .the nonexistence of all affirmative defenses and that, if a state “chooses to recognize a factor that mitigates the degree of criminality or punishment,” then as long as such mitigating circumstance does not serve to negate any of the elements of the criminal offense, the state need not prove the mitigating factor’s nonexistence).
Noting the differences between an element of and an áffirmative-defense to a crime, the Second Circuit has stated: “For these reasons, we have never conflated an affirmative defense as the functional equivalent of an element of an offense, even when ... an element of the crime and the affirmative defense ‘overlap in the sense that evidence to prove the latter will often tend to negate the former.’ ” Aparicio v. Artuz, 269 F.3d 78, 98 (2d Cir.2001) (quoting Martin v. Ohio, 480 U.S. 228, 234, 107 S.Ct. 1098, 94 L.Ed.2d 267 (1987)). We agree; and decline to consider affirmative defenses, such as that in 18 U.S.C. § 2252A(d), that do not directly negate an element of the crime but instead address mitigating circumstances, as “facts” that “require” proof for purposes of the Block-burger analysis.3
*946Having concluded that the conviction presents a problem under the Block-burger analysis, we turn to the dissent’s argument that congressional intent nonetheless mandates that we uphold the multiplicitous conviction. As the dissent notes, “[t]he Blockburger test is a ‘rule of statutory construction,’ and because it serves as a means of discerning congressional purpose the rule should not be controlling where, for example, there is a clear indication of contrary legislative intent.” Albernaz v. United, States, 450 U.S. 333, 340-342, 101 S.Ct. 1137, 67 L.Ed.2d 275 (1981); see also Hunter, 459 U.S. at 368, 103 S.Ct. 673. However, this proclamation retains the basic premise that: “[i]n resolving ... [a] contention that Congress did not intend to authorize multiple punishment for violations of [two statutes], our starting point must be the language of the statutes. Absent a ‘clearly expressed legislative intention to the contrary, that language must ordinarily be regarded as conclusive.’ ” Albernaz, 450 U.S. at 336, 101 S.Ct. 1137 (quoting Consumer Product Safety Comm’n v. GTE Sylvania, Inc., 447 U.S. 102, 108, 100 S.Ct. 2051, 64 L.Ed.2d 766 (1980)).
We disagree with the dissent’s conclusion that Congress has “clearly expressed” a “legislative intention to the contrary.” Relying on Hunter, the dissent argues that Congress, by listing multiple harms associated with child pornography and indicating a purpose to treat child pornography severely, manifested its intent to impose multiple punishments even if the crimes were the same under the Blockburger test. First, the dissent asserts that Congress identified two distinct harms. Yet nowhere in its congressional findings does Congress explicitly frame receipt and possession as two distinct harms; the dissent’s characterization of two distinct harms emanating from receipt and possession, while perhaps reasonable, is superimposed onto Congress’s findings. An equally plausible interpretation of Congress’s findings is that the harms Congress identified emanate from the general existence of child pornography, and relate simultaneously to both receipt and possession of those illicit materials.4
Next, the dissent argues that because under the original 1996 laws receipt and possession were clearly two multiply-punishable crimes under Blockburger, and because Congress intended its 1998 amendments to make child pornography laws tougher, it therefore must be the case that Congress intended that receipt and possession remain separate crimes. The dissent is correct that Congress’s 1998 amendments were motivated by an intent to toughen its child pornography laws. Yet the 1998 amendments achieved that intent in several ways: First, Congress increased some of the penalties for child pornography offenses. See 105 P.L. 314, 202. Second, under the original 1996 law possession of fewer than three images of child pornography was legal regardless of whether one continued to retain those images; thus the law did not take a “zero tolerance” approach as to individuals who possessed only one or two images of child pornography. By contrast, under the 1998 amendment, Congress relegated possession of *947fewer than three images of child pornography to being an affirmative defense to— rather than an element of — the crime, and required that defendants be able to qualify for the defense only by meeting certain additional requirements (e.g., turning over to law enforcement and/or destroying the images). In this sense, Congress adopted a “zero tolerance” approach to possession of child pornography. Congress’s “toughened” stance on child pornography in 1998 did not necessarily include an authorization of multiple and separate punishments for receipt and possession of child pornography for the same conduct.
Though the dissent’s construction of Congress’s intent might be plausible, it cannot be said that Congress “clearly” intended it, especially in light of alternate, plausible interpretations. Hunter did not suggest that the Blockburger analysis be dispensed with; it held only that the presumption against multiple punishment arising from a Blockburger analysis could be overcome by a clear expression of legislative intent to the contrary. Hunter, 459 U.S. at 367, 103 S.Ct. 673. Such a clear expression is absent here, and so the controlling analysis remains that of Blockburger to ascertain whether Congress intended multiple punishments. See Rutledge, 517 U.S. at 304 n. 14, 116 S.Ct. 1241. Even if the matter were “not entirely free from doubt, the doubt must be resolved in favor of lenity.” See Whalen v. United States, 445 U.S. 684, 694, 100 S.Ct. 1432, 63 L.Ed.2d 715 (1980); see also Albernaz, 450 U.S. at 342, 10Í S.Ct. 1137 (“Th[e] policy of lenity means that the Court will not interpret a federal criminal statute so as to increase the penalty that it places on an individual when such an interpretation can be based on no more than a guess as to what Congress intended. We emphasize[ ] that the ‘touchstone’ of the rule of lenity is statutory ambiguity.” (citation and quotations omitted)). If Congress desires to authorize multiple and separate punishments for receipt and possession for the same child pornography conduct, it is of course free to do so. However, until it does, we should not exceed the clearly-expressed legislative authorization.
Having rejected the government’s argument that possession of child , pornography requires proof of an element that receipt does not, we conclude that, under the Blockburger test, the offense of possessing child pornography is a lesser included offense of the receipt of child pornography. Furthermore, given that Congress has not clearly indicated its intent to the contrary, the district court erred when it imposed a second and constitutionally impermissible conviction on Davenport for the same conduct, in violation of the Fifth Amendment’s Double Jeopardy Clause. See Hunter, 459 U.S. at 366, 103 S.Ct. 673. The fact that the terms of. the two sentences run concurrently does not alter our conclusion. See Ball, 470 U.S. at 864-65, 105 S.Ct. 1668 (discussing potential adverse collateral consequences of sentences violating double jeopardy, even if concurrent, and concluding that “[t]he second conviction, even if it results in no greater sentence, is an impermissible punishment.”).5
The district court’s error was plain, and it affected Davenport’s substantial rights by imposing on him the potential collateral consequences of an additional conviction. Finally, because the prohibition against double jeopardy is a cornerstone of our *948system of constitutional criminal procedure, this error threatens the fairness, integrity, and public reputation of our judicial proceedings. We therefore exercise our discretion under Olano to correct it.
We vacate the judgment and remand with instructions that the district court vacate Davenport’s conviction on one of the two counts, allowing for it to be reinstated without prejudice if his other conviction should be overturned on direct or collateral review.
VACATED AND REMANDED.
. Davenport's other claims relating to the denial of his motion to withdraw his guilty plea and to his sentence are the subject of a separate, unpublished memorandum disposition filed contemporaneously with this opinion.
. Because we accept the position of the parties with regard to the element of interstate shipment, we need not address the government’s additional point that it is possible to be guilty of possessing pornography knowingly without having knowingly received it.
. Some affirmative defenses, by contrast, negate one or more of the elements required for a crime. Different principles apply to such affirmative defenses: "[i]f a[n affirmative] defense negates an element of the crime, rather than mitigates culpability once guilt is proven, it is unconstitutional to put the burden of proof on the defendant.” United States v. Solorzano-Rivera, 368 F.3d 1073, 1079 (9th Cir.2004) (citing Walker v. Endell, 850 F.2d 470, 472 (9th Cir.1988)). Thus, such an affir*946mative defense would in reality be an element requiring the government's proof of the converse of the affirmative defense beyond a reasonable doubt. However, the affirmative defense in 18 U.S.C. § 2252A(d) is not such a defense; it concerns mitigating circumstance and does not negate one of possession’s elements.
. Cf. Rutledge, 517 U.S. at 304, 116 S.Ct. 1241 ("If anything, the proximity [in the U.S.Code of the two crimes at issue] indicates that Congress understood them to be directed to similar, rather than separate, evils.”).
. Davenport also suggests that his sentence for both possession and receipt of child pornography presents a problem under United States v. Booker, 543 U.S. 220, 125 S.Ct. 738, 160 L.Ed.2d 621 (2005), which requires that we analyze a sentence for "reasonableness.” See United States v. Cantrell, 433 F.3d 1269, 1280 (9th Cir.2006). We need not reach this argument because of our conclusion that Davenport's sentence is constitutionally infirm because of double jeopardy.