Because that's happened to me, there were many times a bank teller had older notes for me, UNC, in sequential order only to find they had deep creases put on the corners and center of the bills in different places. The creases were deep, like somebody folded, then ran their fingernail along to crease to make it deep and permanent. Anyway, I think I'm just about the only collector in my town, so I don't think too many other are interested.