1972 Double Die Cent
In 1972 workers at the Philadelphia Mint made a mistake. While making a die that was used to mint cents, a misalignment occurred causing the die with Lincoln's portrait to have doubled letters and date. About 75,000 pieces were released before the error was discovered.
If you have this cent, it will have distinct doubling on the word Liberty, the word "In" will appear to have two "I"'s and the date will show two distinct impressions. If genuine, average pieces are worth at least $175. Occasionally uncirculated specimens are found in a bank wrapped roll of cents. These coins can be worth hundreds of dollars.
To be certain your coin is genuine, you should have authenticated and graded by a third party grading service, such as the Numismatic Guaranty Corporation (NGC) or Professional Coin Grading Service (PCGS). You may submit coins directly to NGC if you are a member of the American Numismatic Association (ANA) or to PCGS if you join the PCGS Collector's Club. You may also submit your coins through an authorized dealer.
To Learn more about another cent with a doubled image, see the article about 1955 double die cents.