Dual Denomination

A double denomination is when an already struck coin is struck by dies intended for another denomination. An example is a struck dime over-struck by dies intended for a Lincoln Cent and this example is often pet-named 11 cents.
Values for double denomination errors can vary widely and depends on the dates and denomination as well as what grade is placed on the coin holder. The Roosevelt Dime over Lincoln Memorial Cent in the image above can trade for over $300 and the half dollar struck over a Susan Anthony Dollar can trade for over $22,000.