We all know what precise quality is made in forgery stamps which will be very hard to identify because there are very rare to compare with so you will think forgery as genuine itself.!!
Following is King George stamp but it is replica and if seller don't mention it then you will think it as genuine without a doubt.
So what are chances of this stamp sold as Mint stamp or what are chances this stamp is selling used stamps after applying forged rubber stamp or what are chances this stamps selling on used register cover or piece of paper.!!
I think that's the only use of this kind of replica or facsimile or forgery stamps as no one like to collect FORGERY.!!
Now compare above stamps of KG stamps of 10 shillings and you decide what are chances that some higher value forgery stamps are mixed with this lot.