(1) Upon the production of an instrument chargeable with any duty as evidence in any court, or in judge's chambers, or before the Registrar, notice shall be taken by the judge, magistrate or Registrar, that such instrument is unstamped or insufficiently stamped, and it shall be the duty of the Registrar or clerk of the Court to call the attention of the judge or magistrate to the fact that such instrument is unstamped or insufficiently stamped; and if the instrument is one which may legally be stamped after the execution thereof, it may, on payment to the Registrar or the clerk of the Court, as the case may be, of the amount of the unpaid duty and the penalty payable under this Act on stamping the same and of a further penalty of $2.50, be received in evidence, saving all just exceptions on other grounds.