Forgeries of rare postage stamps have been around a long time and they are fairly common.
Less common are forgeries produced to defraud the postal authorities.
This is not surprising. Why would a master forger risk ten years in prison just to save buying a stamp worth 50 cents?
Here is an example from Singapore (50 cent blue) of a forgery which was used on an envelope alongside two genuine stamps and, since it is postmarked , it appears to have slipped past the postal authority unnoticed.
This type of postal forgery is relatively scarce and sought after by collectors.
The problem for collectors though is that fraudsters have been known to forge forgeries. For example a forged stamp could be applied to an envelope after it has been through the post and, with a careful touch-up of the postmark, be made to appear like the example above.
Crooks are not the only ones to have used forgeries. During WWII both the Allies and the Germans produced forged stamps for propaganda purposes.
One of the more amusing examples was made by the British during 1943. It parodies an actual Italian stamp but shows a shocked Mussolini getting a telling off from Hitler. The caption on the original stamp read ‘Due popoli una Guerra’ (two peoples, one war). This was replaced with ‘Due popoli un führer’! It probably didn’t make much impact on the war effort but no doubt it raised the morale of Allied stamp collectors.