(1) Upon accusation of a charge of perjury by single statement, as defined in Section 491 of Title 21, it is a defense that the statement is true.
(2) Upon accusation of a charge of perjury by contradictory statements, as defined in Section 496 of Title 21, it is a defense that the accused at the time he made each statement believed the statement was true. Laws 1965, c. 126, § 4.