Jill.. You have an authentic "altered coin" ;-) Some unscrupulous people make things like these up out in the garage and try to sell them to folks as "rare errors" I beleive the process for making a double date coin like this is to take a 1973 cent and put it between two blocks of wood and compress it tightly in a vise to transfer the desigh to the wood.. then take that piece of wood and your 1977 cent and squeeze it tighly in the same vise, raising the metal of the 1977 cent slightly into the pattern left in the wood by the previous coin and making your double date coin. Incedently, some numismatists might take offense at you calling it a "penny" The US Mint does not make "pennies" they are called cents.. Pennies are made in Great Britain or Australia. The terminology doesn't bother me, though.. I have about 50 bags of wheat cents and about a ton and a half of uncirculated memorial "pennies" laying around the office that I need to get busy and make up ebay ads for so I can clear the space and buy more chips!