There are error coins that many collectors view as the one coin that they would love to own. For many, this coin or coins represent the holy grail of their collection and there are few that rank as high as the double denominations error. This one error type is one of the most valuable and rare errors that have ever been released from the mint.

Double denominations occur when a previously struck coin is struck again by another set of dies in another denomination. Often times this is the result of the mint using a coin to test the dies and somehow the test coin escapes the mint. It is thought that this occurs because a worker smuggles the coin out of the mint because they know that such an example would be worth a good amount of money. Other times it simply slips through the cracks.

Double denominations are not coins that one would easily find in pocket change but it is not unheard of to catch one if you are very lucky. This is the case with one of the most famous double denomination coins that have been found in recent years.

A man who worked in a gas station received a coin that he thought to be a foreign dime. Later on in the evening he checked the coin again only to discover that what he had was what has come to be known as an 11 cent piece. The coin was a previously struck Roosevelt dime and a Lincoln cent had been struck over it.

This is something that happens once in a lifetime. There are other examples of the double denominations error but they are very difficult to come by. Some of the more prolific error coin dealers have some fine specimens but they sell for more than $100,000 in the open market and can reach prices of more than double that amount in a well advertised auction setting.

You should be careful when purchasing a double denomination coin that is priced well below market value. There are fakes floating around that have little or no value at all. Sadly many people in the world will try and take advantage of the new collectors and sell coins that are nothing more than reproduced errors. Do your homework and protect yourself from making a bad investment.