Die break which include the rim of a coin. (see pic in post #1:smile) When you see die cracks, the die has developed cracks. When part of die eventually breaks away, it leaves a void which is filled with metal when the coin is struck leaving a large or small lump where the design in the die no longer exists. If this happens on the interior of a coin, it is called a die break or die chip.
Prospector, I agree it doesn't match any of the 7 DDO on coppercoins, nor any extra markers in Crawford's Lincoln cent Varieties. It is a little hard to see from the photos if the doubled appearing portion is raised to the same level as the main detail. I assume you have checked the die scratches and such also for the lesser ones ( 4-7). Interesting coin. Jim