Whoever having already been convicted of an offence under section 39 or section 40 is again convicted of any such offence shall be punishable for the second and for every subsequent offence, with imprisonment for a term which shall not be less than one year but which may extend to three years and with fine which shall not be less than one lakh rupees but which may extend to two lakh rupees:

Provided that the court may, for adequate and special reason to be mentioned in the judgment, impose a sentence of imprisonment for a term of less than one year or a fine of less than one lakh rupees:

Provided further that for the purposes of this section, no cognizance shall be taken of any conviction made before the commencement of this Act.