When a person has made inconsistent statements under oath, both having been made within the period of the statute of limitations, the prosecution may proceed by setting forth the inconsistent statements in a single charge alleging in the alternative that one or the other was false and not believed by the defendant. In such case it shall not be necessary for the prosecution to prove which statement was false but only that one or the other was false and not believed by the defendant to be true.
A.R.S. § 13-2705