As noted by P&G...deterioration. As a general note, anytime the Monticello has the appearance of doubling, it is almost always the result of a worn die. Off the top of my head, I can't think of a single DDR where the Monticello was significantly doubled (readily discernable by eye). The modern, single squeeze DDRs do have doubling of features within the Monticello, generally in the center of the coin, but even then, it's a feature or two rather than the Monticello itself.
Yep, die deterioration doubling caused by worn dies. Similar to mechanical/mechanical doubling in looks.
