There have been numerous attempts to “manipulate the system” with Revenue Stamps.
1. Postal-type cancellations
Many examples exist of Revenue Stamps which have been cleaned of their manuscript cancellations and postmarked with postal-type cancellations in an attempt to command a higher price for the stamp. Doubts also exist about the genuineness of postal-looking cancellations from the 1870 – 1910 period.
Click on the link below for a guide to how to identify these stamps, and othe factors to be aware of when looking for a “postally used” example