Jeff Makkos of Ohio reports finding a double struck 2007-P James Madison dollar in a Mint-issue set. The type of double strike involved is what errorists refer to as an “In-Collar Double Strike with Rotation Between Strikes.”The cause may be due to two different scenarios.
The first possibility is that the coin was struck normally and then reentered the coining area falling back over the collar where it was forced back into the collar by a second strike in a position rotated just a few degrees away from the original strike.
Another possibility suggested by CONECA president Mike Diamond, is that coin remained in the collar while the inner sleeve of the collar broke loose and rotated within resulting in the same effect.
Source: NN, 08 April 2008.