Die doubling is the type of doubling that exhibits a doubled image on the die itself, even before the coin is produced. Die doubling includes doubled dies, repunched dates, repunched mintmarks, overdates, over mintmarks and repunched letters.

Typically die doubling will almost always exhibit splits in the serifs of the letters and/or numerals, with rounded, secondary images.

Many Nineteenth Century coins have letters and numerals which are flat on their top surfaces as compared with the rounder appearance of most Twentieth century letters and numerals. Therefore, the key to identifying true die doubling on Nineteenth Century coins will be the distinctive splits in the serifs.

There is one class of doubled die which would not exhibit the normal characteristics mentioned for die doubling. Known as Class VI doubled dies, these exhibit extreme extra thickness on some letters and numbers. Most widely known on Lincoln cents, the doubling usually will exhibit a letter E or L with a convex (downward looping) horizontal stroke, and the letter U with an extremely thick loop. Although some specialists may disagree, these doubled dies generally command very little premiums – except in rare cases.