(concurring).
I join in the majority opinion by Mr. Justice Eagen. I should like to add that the issue of double jeopardy is similar to an issue of subject matter jurisdiction. It may be raised at any time, even initially on appeal. Constitutionally, no court has jurisdiction to try or sentence a person twice, in violation of the Federal and Pennsylvania Constitutions. See Commonwealth v. Walker, 468 Pa. 323, 362 A.2d 227 (1976) (filed June 6, 1976).