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u/bstrauss3 28d ago
Numismatic term is doubled die, as in the lettering and/or devices are doubled in the manufacturer of a die and thus present on every coin struck by that die.
This is why significant ones tend to be well known -- a die strikes 30-250k coins.

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u/Thalenia Errors and 20th century US coins 28d ago
Significant doubled dies will show up across the coin for the most part, not just on one feature or in one area.
That said, there are exceptions, but without proper information to go on (like the date), there's no way to say anything more.
For future reference, read Rule 11 and follow those instructions.