Flat and shelf-like. It is machine doubling (with possible die deterioration doubling present as well). Notice how the doubling cuts into the design rather than adds to it. Not a doubled die. Keep up the hunt!
One way to determine if it is the 1960 DDR-023 is the center bar will be almost completely missing in the B in PLURIBUS.
geek, If he had called it a double-die, I dont think it would have received as many bids. Sadly, there are the uninformed who believe this is an exclusive error. miles, good eye, nonetheless.