Where an act or omission constitutes an offence punishable under this Act and also under sections 166A, 354A, 354B, 354C, 354D, 370, 370A, 375, 376, 376A, 376C, 376D, 376E or section 509 of the Indian Penal Code (45 of 1860), then, notwithstanding anything contained in any law for the time being in force, the offender found guilty of such offence shall be liable to punishment only under this Act or under the Indian Penal Code as provides for punishment which is greater in degree.