I pulled this out of a bu roll tonight roll hunting. One side has a normal strike, the obverse appears to have Lincoln's head struck over from another pennies reverse. You can see one cent spelled in reverse. My first post here.
Woah! That's an awesome mint error you've got there. It's actually not a 'two tailed cent'. It's referred to in the numismatic world as a 'brockage' error. They're pretty hard to find and you have a really nice example of one. I'd say it's worth at least $10 to an error coin collector. Here are some links that explains different types of mint errors. The link Rick provided is also great. The example they show are a quarter and a nickel but it can happen on any denomination. http://jimscoins.com/error_coin_examples.php https://en.wikipedia.org/wiki/Brockage
