When a person has made 2 statements under oath which are inconsistent to the degree that 1 of them is necessarily false, and the circumstances are such that each statement, if false, is perjurious, the inability of the prosecution to establish specifically which of the 2 statements is the false one does not preclude a prosecution for perjury. The prosecution may be conducted as follows:
(1) The indictment or information may set forth the 2 statements and, without designating either, charge that 1 of them is false and perjurious.
(2) The falsity of one or the other of the 2 statements may be established by proof of their irreconcilable inconsistency. Such proof is sufficient to establish a prima facie case of falsity.
(3) If perjury of different degrees would be established by the making of the 2 statements, hypothetically assuming that each is false and perjurious, the defendant may be convicted of the lesser degree at most.