The error fakes that are plaguing coins are in full force in paper money as well. I report at least one a day now and there is no telling how many I miss seeing. This one is an example: https://www.ebay.com/itm/203991223650?hash=item2f7ed30d62:g:O-cAAOSwT8pipkCO Its not even a good fake Edit to add photo.
This was a magic trick shown on YouTube. http://1streetmagic.com/david_blaine/David-Blaine-move-seal-on-dollar-bill.htm https://www.answers.com/Q/How_do_you_move_a_seal_on_a_dollar_bill
https://www.ebay.com/itm/325212236004?_trkparms=amclksrc=ITM&aid=1110006&algo=HOMESPLICE.SIM&ao=1&asc=20200818142055&meid=910ba30a122c4b98a642323be7802bfa&pid=101113&rk=7&rkt=12&sd=284786208320&itm=325212236004&pmt=1&noa=1&pg=2563228&algv=DefaultOrganicWeb&_trksid=p2563228.c101113.m2108 What's the chances that no one notices the serial numbers rubbed off of the $5 bill?
https://www.ebay.com/itm/354137775861?_trkparms=amclksrc=ITM&aid=1110006&algo=HOMESPLICE.SIM&ao=1&asc=20191002094254&meid=94c6e067aa5d4a34bd530fa5724c8d3a&pid=100891&rk=1&rkt=6&sd=144627088491&itm=354137775861&pmt=0&noa=1&pg=2332490&algv=DefaultOrganicWeb&_trksid=p2332490.c100891.m5207