30. (1) Whoever, having been convicted of an offence under section 27, is again convicted of an offence under that section shall be punishable with imprisonment which may extend to five years, or with fine, or with both. (2) Whoever, having been convicted of an offence under section 28 or section 29, is again convicted of an offence under either of those sections shall be punishable with imprisonment which may extend to two years, or with fine, or with both.