Perjury requires FALSE, not CONTRADICTORY, statements

A conviction for perjury cannot be sustained merely upon the contradictory sworn statements of the accused. In perjury, the prosecution must prove which of the two statements is false and must show the statement to be false by other evidence than the contradicting statement. (Villanueva vs. Secretary of Justice, G.R. No. 162187, 18 November 2005, 475 SCRA 495)