We have pieces like this come into the store periodically.The stuff that looks like glue...IS glue. What you have here is the center coin from a three-coin "sandwich" that was glued together. When the other two outer coins were peeled away, the reversed impressions from their designs were left in the glue stuck to each side of your piece. This isn't a mint error. Want proof? Soak the coin in some nail polish remover (acetone). The glue will disappear along with the designs, and you'll be left with a normal Lincoln Cent. Value...one cent. Sorry.
Don't blame me-I voted for the American.