Stamp collectors are probably more finicky that coin collectors and worry about every single perforation, centering, coloring, and countless other details as to the gum, tears, folds, etc. I mention this because not long ago an ardent stamp collector had misplaced his 24 inverted airmail stamp. He turned his study upside-down. And despite all the efforts made by our government, errors appear, some quite gross. Perfection is something that is strived for, not necessarily achieved.
Error coins command a premium, and the greater the error, the greater the premium.
Well, it's an error coin. It is what is called a silver penny, or an eleven cent coin. It is a Lincoln cent minted on a dime planchet. It is caused supposedly when there is a changeover from one minting process to another. After minting dimes, one or more planchets may still be left in the hamper.