I would guess that because this particular item was part of a botched mass-production run it might be possible to perform checks that are not available for a pi

I would guess that because this particular item was part of a botched mass-production run it might be possible to perform checks that are not available for a piece of art. Do the edges of #49 match up with any other available samples? Beyond simple chemical tests that will be performed is it possible to match up the actual paper fibers; both directionality and even if cut lines in fibers match up with edges of the stamps around it on the master sheet? In addition to testing it like a piece of art you can also test it as if it were a piece of a puzzle (the master sheet) to make sure it fits into place. I am not sure if the information necessary to fake this is out there or not, but the fact that this stamp is cut out of a sheet makes it a bit different than a painting.