Hey! Haven't had much luck differentiating between worthless doubling and actual doubled dies yet, so won't claim to know exactly what this is. Definitely appreciate your guys' input!
Struck with a seriously worn, not doubled, die. Here's a site where you can get good info. http://doubleddie.com/1801.html Happy hunting!
Some of what you are seeing is worn die. Some is wear and tear. And some is machine doubling. I don't have a link right in front of me. But, google "trail die". There is a site dedicated to trail dies. It will give you a better explanation of what you are seeing. The pic of "PLURI" shows trails from the "U" clearly. This comes from the hubbing process of the working die. There is slippage between the working die and master hubbing die. According to this site this slippage also creates a form of doubling. A trail die and a doubled die do not necessarily go hand in hand.
I believe what you are seeing at the U of PLURIBUS is die deterioration, not die trails. Die trails would come primarily from the serif of the U. In this case you are seeing deterioration of the die stringing out all along the right vertical of the U.