All the classes of double dies are made from machine ( human ) error . Lol . actually some of the class II also bring money . Just my opinion of course ..
Perhaps more for the mix - http://www.varietyvista.com/07 Roosevelt Dimes/Obverse Design Varieties.htm.
I am very very new. I've been collecting coins for years but never sell them. Last summer I received 5 uncirculated penny roles that were all 1958 (all marks and not marked) along with 70s coins, the good ones. I live in a small town and the local bank owned by same man for 70 years. My guess is that last year when coin shortage came, they got into his stash as the bank is the ones who gave them! He had specific 80's too. The good ones. I've been a watcher of the coins sites but never get on to ask questions. Now, status quo change so I have to get serious. I do have some good ones. I do know what to look for, on a very limited scale, but I have this crazy vision that I normally see dimensionally anyway when looking at objects - that helps. I don't even know where to start.