Here is another of my favorite RPMs. It's the 1956-D/D Secondary D encroaching into the 9 of date. This coin has an interesting history.
For several years before he passed, the late Reg Martin of Michigan used to tell me that he had a 1956-D cent with an extra D up in the 9 of date. I kept saying that he must be mistaken, that the seperate D for that year was South of the primary D (back in this days only RPM#8 was known with a separate D for that date). But he insisted. For a couple years we talked about me coming to his house that I think was around Grand Rapids, Michigan and so in time we decided to get together one winter day. As it turned out, we had pretty bad weather and I had to delay my trip and when I called later we had to cancel due to a conflict in his schedule. Unfortunately, I never saw Reg again as he passed on of cancer.
In time, his wife decided to sell his collection through a local dealer who knew Reg well and knew his varieties. I purchased a number of his coins individually and eventually purchased the remaining stock as a lot.
Reg had tons of RPM Lincolns in his collection and I never found time to merge it in with my collection (and in fact I still have not found time so many years later).
Then I heard about a report of a 1956-D Lincoln with a D up in the 9. As soon as I heard this I pulled Reg's boxes of RPMs and looked through the area where the 1956-D varieties were and there it was -- the coin he held so much pride in for those years we got together to talk RPMs and Doubled Dies. Today, I own it and will take it to the grave with me like Reg did.

CONECA: RPM-016, Wexler: RPM-023, Coppercoins: 1956D-1MM-016, Crawford: CRPM-003