Doubled dies are dies that show more than one impression from the hub. This doubling of the die occurs when a subsequent impression of the hub into the die is not perfectly aligned with the first impression. This process is similar to using an ink stamp; can you imagine trying to position the stamp to strike the same exact spot on the paper several times? The modern die making process includes single-squeeze hubbing, so this practice almost eliminates the possibility of a doubled die. But back in the day, dies often had to be hubbed many times to get the proper relief needed to make a suitable coin. A single hubbing would only impart faint remnants of the design.
There are 8 recognized classes of doubled dies:
- Class 1, Rotated – A class I doubled die results when the die receives an additional hubbing that is misaligned in a clockwise or counterclockwise direction.
- Class 2, Distorted – A class 2 doubled die results when the hub’s design moves toward the rim between hubbings.
- Class 3, Design – A class 3 doubled die results when a hub bearing a different design stamps a die bearing another design.
- Class 4, Offset – A class 4 doubled die results when the die receives an additional hubbing that is misaligned in an offset direction.
- Class 5, Pivoted – A class 5 doubled die results when the die receives an additional hubbing that was misaligned via rotation with a pivot point near the rim.
- Class 6, Distended – A class 6 doubled die results when the die receives an additional hubbing from a hub that was distended.
- Class 7, Modified – A class 7 doubled die results when the hub is modified between the die’s hubbings (e.g., a design element was chiseled off).
- Class 8, Tilted – A class 8 doubled die results when a die and/or hub is tilted during a hubbing.
John Wexler, the leading authority on Lincoln Cents, has published excellent research into the die making process and doubled dies. Coins can exhibit not only a doubled die, but a tripled die or even a quadrupled die! Please see John’s site here: http://doubleddie.com/58222.html
Examples of Doubled Dies
1857 DDO-007 – Flying Eagle Cent Doubled Die Obverse
1873 DDO-001 – Indian Head Cent Doubled Die Obverse
1905 DDR-002 – Indian Head Cent Doubled Die Reverse
1890 QDO-001 – Indian Head Cent Quadrupled Die Obverse
List sourced from https://en.wikipedia.org/wiki/Doubled_die#Classes_of_Doubled_Dies