Enhanced penalty after previous conviction

Whoever having been convicted of an offence punishable under sub-section (1) of section 27, or clause (a) of sub-section (1) of section 28, or section 29, or section 33 is again found guilty of an offence punishable under the same provision, shall be subject for every such subsequent offence, to a fine which may extend to two times of the amount of fine provided in such provision.