Stamp duty on cancellation deed of agreement to sale

In Maharashtra, you are entitled to claim refund of the stamp duty, within six months from its payment, in certain situations. You can claim the refund of stamp duty paid on such instrument, if the same has not been executed. The government deducts 1% of the stamp duty, subject to a minimum of Rs 200 and a maximum of Rs 1,000 of the stamp duty paid.

The stamp duty rate will be vary from state to state Therefore better to consult local lawyer or directly approach the registration office

Considering you have executed and registered the deed by paying appropriate stamp duty, the cancellation deed will not cost you any further stamp duty, only minimal charges are applicable, however this can be different form state to state so please consult a local layer.