Ken Potter's Educational Series ...

11-cent piece explained

by Ken Potter - NLG
December 27, 1998
Ken Potter 1998

One of the most dramatic and highly collectable of the striking errors is the "double denomination", or in the case of the Lincoln cent, what is affectionately referred to by collectors as an "11-cent piece." The error type is so eye appealing and mesmerizing that even non-error collectors frequently do a "double-take" and an example or two in a dealer's
showcase is likely to draw crowds of non-collectors as individuals drag friends and relatives over for a finger-pointing session of the ‘freak-show’ followed by the inevitable inquiries as to how they got out of the Mint. The "11-cent piece" is also one of the few error coins that has so much collector appeal that it could almost be termed a "cross-over coin" as it’s one of the few errors that many non-error coin dealer will stock and many non-error coin collectors will buy.

As the name implies, the error involves the striking of a planchet by the dies of two different denominations. The 1991 Lincoln cent (illustrated in the photo supplied by Alan Herbert), was first struck normally by ten-cent dies and was then transported to another press and stuck a second time by one-cent dies. This one is known as a "flip-over" because the ten-cent design was stuck by the one-cent dies, reverse to obverse. It would also be described as showing two dates as both the Lincoln cent and Roosevelt dime dates are visible. Although the final digit of the understrike is flattened out and a bit harder to see the fact it can be seen qualifies it as showing two full dates. The desirability of an 11-cent piece is often gauged by the amount of detail that is present from both strikes. If the understrike is difficult to view due to a stronger strike than average by the cent dies then it is considered less desirable than a strike that shows an almost equally matched composite design from both denominations. While I’ve seen better examples, the one shown is a better than average strike with lots of collector appeal. This particular piece sold for about $400 several years ago.

This error type occurs most frequently when a tote bin fails to be emptied all the way and a struck dime (or more) from a previous operation remains stuck in a corner or in the groove of a tote bin door. It the bin is then used to transport planchets for one cent coins to a press for striking, the struck dimes may get mixed in and struck a second time as a Lincoln cent.

Ken Potter is the official attributor and lister of world doubled dies for the Combined Organizations of Numismatic Error Collectors of America and for the National Collectors Association of Die Doubling. He privately lists U.S. doubled dies and other collectable variety types on both U.S. and world coins in the Variety Coin Register.

For more information on either of the clubs, or on how to get a variety listed in the Variety Coin Register he may be contacted at:   An Educational Image Gallery may be accessed on his website at:

Ken Potter
P.O. Box 760232
Lathrup Village, MI 48076-0232

  Phone: 1-(313)255-8907   E-mail:
Numismatist Since 1959 ~ Serving the Collector Since 1973

CONECA's Longest Serving Doubled Die Attributer


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