Evidence of clashed dies is not common, but on proof dies, it is extremely rare. In this particular case a 2011 proof Army Commemorative  obverse shows visual indication that the obverse die clashed upon a reverse die. However the reverse die does not show any indication of reciprocal clash marks suggesting that a Mint employee probably switched out the reverse die, and for an unknown time, left in the obverse die to strike blanks into coins.

The first illustration shows an approximation overlay diagram showing the position in which the dies appear to have struck one another.

Next, in the lowest point between the two helmets, we see clash marks of the shield, the outline of eagle's neck, ribbon and the negative space between them and the eagle's feathered wing

 

A closeup of the overlay diagram showing the areas in question.

 

 

 

 

Above the helmets on the globe, the tail feathers of the eagle are seen and to the left a small portion of the U of U.S. appears.

 

 

The U from U.S.

 

 

 

 

 

The tail-feathers close up.

 

 

 

 

 

 

 

 

 

 

Parts of the shield and eagle's wing

 

 

 

 

 

 

The eagle's neck, ribbon and some feathers.

 

 

 

 

 

 

The US from PLURIBUS, more ribbon, and the rays from the "Great Seal of the United States" that appears above the eagle.

 

 

 

 

 

 

 

More rays from the Great Seal.

 

 

 

 

 

And a more complete view of the negative space between the ribbon and eagle's wing .

Coin found by:
Louis Schaeffer