I would agree that it is mechanical doubling.
The coin is showing signs of heavy die fatigue (die wear, die deterioration). It's rather common in nickels of this period.
Definitely a "grease strike". The coin was struck through a layer of gunk that clogged the recesses of the die. These sorts of errors are also...
It looks like a die chip. This is a pretty common area for chipping to occur in Lincoln cents.
Struck through some sort of coarse substance. Too rough for grease proper, but possibly a conglomeration of grease and metal dust.
Peculiar, especially if the doubling is restricted to this one digit. It's hard to say what kind of doubling this is without a close inspection...
This is not machine doubling but appears instead to be a peculiar form of die deterioration doubling that is largely or exclusively restricted to...
Looks like a dirty, stained, corroded cent to me.
On the "ghost" cent, check the rim and edge. If the design rim is absent, and if the rim/edge junction is beveled, then it's a weak strike. In...
All excellent references. Pleased be advised, though, that "abrasion doubling" is largely a myth. The vast majority of coins paraded as examples...
It's a scratch from a coin wrapping machine.
Depends what your baseline is. Compared to the total number of coins struck, these errors are rare. Compared to other types of errors, capped...
This is a capped die strike. The coin was struck through an obverse die cap. The cap had a wrinkled surface, which is pretty common. The cap...
The vast majority of these "bubbles" are created outside the mint, evidently by applying a source of heat, such as a blowtorch flame. As a...
What do you mean by a "color change"? Any warping is not a good sign.
Both photos are still too fuzzy to be sure of anything. On the left side, does the obverse show any warping or distortion? Is the rim/edge...
1981 is far too early for an inverted die setup. The mint didn't start toying with obverse die as anvil die until 1992. This coin could have...
Another uncentered broadstrike. Almost an off-center strike. If part of the reverse design is cut off, then you could call it an off-center...
My diagnosis remains unchanged. However, I see you also have a slight horizontal misalignment of the obverse die.
It looks like the 2000-D cent is a combination error -- foreign planchet and a modest strike-through error. These foreign planchets come from the...
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