If any provision of this chapter is less stringent or requires information different from any requirement of Section 4 of the act of Congress entitled “Fair Packaging and Labeling Act” (P.L. 89-755; 80 Stat. 1296; 15 U.S.C. 1451-1461) or of any regulation promulgated pursuant to that act, the provision is inoperative to the extent that it is less stringent or requires information different from the federal requirement, in which event the federal requirement is a part of this chapter.