(1)Notwithstanding anything contained in section 4 or 6 or in any other enactment, unless it is proved that the duty chargeable under this Act has been paid,-(a)on the principal or original instrument, as the case may be, or(b)in accordance with the provisions of this section,the duty chargeable on an instrument of sale, mortgage or settlement other than a principal instrument or on a counterpart, duplicate or copy of any instrument shall, if the principal or original instrument would, when received in this State have been chargeable under this Act with a higher rate of duty, be the duty with which the principal or original instrument would have been chargeable under section 19.
