i just discovered a 1 dollar bill that has all of he 4's (the four numbers 2 on each side) and the federal reserve bank seal that printed thru the bill. it is very dark and reversed on the back. how common is this?
It's not printed through, it's an offset error. Usually, part or all of a prior note was missing. The ink intended for the missing part wound up being printed on part of the press machinery instead. When the following notes came through, they got a reversed impression from the wayward ink on their opposite sides. The first such impression is quite dark, and several impressions, each a little lighter, appear on the next few notes. Sounds like your note has an offset from the black portion of the third printing (seals and serial numbers). It's not very common (well it happens a lot, but most misprinted notes don't make it through the inspection process).
