Section 31. The commissioner shall redeem any unused or mutilated but identifiable stamps that any stamper may present for redemption; provided, that they were originally lawfully purchased by the stamper who presents them for redemption. Such redemption shall be made at the face value thereof less allowances made for compensation. The commissioner may prescribe necessary rules and regulations for redemptions under this section. If the commissioner is satisfied that a stamper is entitled to a redemption he shall issue to him stamps of equivalent value to cover the mutilated stamps or he may order a refund equal to the actual amount paid for said unused or mutilated stamps, and shall certify said amount to the comptroller, whereupon the state treasurer shall pay the amount of such refund without any appropriation therefor by the general court.