21. Any offence against the third or fourth paragraph of section 12 shall render the offender liable,(1) in the case of a natural person, to a fine of not less than $2,000 and not more than $25,000 for a first offence, and to a fine of not less than $4,000 and not more than $50,000 for a second or subsequent conviction; or
(2) in the case of a legal person, to a fine of not less than $4,000 and not more than $500,000 for a first offence, to a fine of not less than $8,000 and not more than $500,000 for a second conviction, and to a fine of not less than $20,000 and not more than $500,000 for a subsequent conviction.