Die deterioration. It always appears on the sides of the devices closest to the nearest rim.
Machine Doubling can be on one side or the other or in multiple directions on the same coin. (MD does have any set rules. Because it is a machine issue after the strike, it does what it can do at random from strike to strike)

If you look on Wexler's double die site, you will see that almost all of the
DDO's on these quarters are on the earlobe area. (usually the only area affected on these single squeeze areas are the centers of the designs)
States quarters:
http://www.doubleddie.com/179401.html ATB Quarters:
http://www.doubleddie.com/719755.htmlSo save your money. They are not
DDO's.