(a) Any person who violates section 604(a)(1) of this chapter by distributing a controlled substance to a person under eighteen years of age is (except as provided in subsection (b) of this section) punishable by (1) a term of imprisonment and a fine equal to twice that authorized by section 604(b), and (2) equal to twice any special parole term authorized by section 604(b), for a first offense involving the same controlled substance and schedule.
(b) Any person at least eighteen years of age who violates section 604(a)(1) by distributing a controlled substance to a person under eighteen years of age after a prior conviction or convictions under subsection (a) of this section have become final, is punishable by (1) a term of imprisonment and a fine equal to three times that authorized by section 604(b), and (2) equal to three times any special parole term authorized by section 604(b), for a second or subsequent offense involving the same controlled substance and schedule.