We'll need clearer photos to tell, and you'll probably need to take the coin out of its holder. It could be a "struck through grease" error. It's also possible that it's not a real coin; it looks odd to me in these photos. The green color on the reverse could be verdigris, or it could be PVC damage from plastic in a holder. Welcome to CoinTalk!
Something does look off, but that could be the flip it is in. Please post some photos out of the flip. This coin may need some restoration help.
Can't tell with the coin in the flip and the lighting but probably a grease or debris filled Die which is still common today. Welcome to CT.
@Ben88 With the rust on the staples, a new 2x2 would help, so removing it for pics won't hurt. Also, you may want to review how you store the coins because the rust is an indication that it's exposed to excessive moisture, which isn't good in the long run. Finally, I agree with @-jeffB There may be PVC plasticizer residue on the surface which is acidic and will damage the coin. There are a number of posts in the archives that can help you remove this using a solvent without damaging the coin. Search PVC. Welcome to CT
