Is it possible to get a refund of stamp duty already paid on an instrument?

Yes. If stamp duty is paid on an instrument but the instrument is not signed by any party, then an application is to be made within 6 months of the date of purchase of the stamp paper, to the concerned authorities for refund of stamp duty. The original stamp paper is returned along with the application. On receipt of such application, the concerned authorities are empowered to refund the value of stamp duty after deducting such amounts as may be prescribed.