Where, in the course of one or more official proceedings, a person makes inconsistent statements under oath, the prosecution may proceed by setting forth the inconsistent statements in a single count alleging in the alternative that one or the other was false and known by the defendant to be false. In such case it shall not be necessary for the prosecution to prove which material statement was false but only that one or the other was false and known by the defendant to be false. For purposes of this section, no corroboration shall be required of either inconsistent statement. (Ord. 1145-85 § 66, 1985.)