There was a lot going on at the Denver mint in 1956, mostly with wandering mint marks. But one of the controversial cents that showed up was this one, originally listed by CONECA as DDO-001 (a doubled die) and by Wexler as WRPD-001 (a repunched date).
Well given that a repunched date seems impossible for a 1956-D coin, both CONECA and Wexler pulled their listings and now it is just considered random die damage that looks like an extra 5.
Even though this isn't actually anything, it was originally a DDO-001 so have been looking for a slabbed and labeled one to add to the collection. Saw this come up and got it for $22. Would still love to find one with DDO-001 on the slab, but not even sure any were done that way.
1956-D Lincoln Wheat cent
debunked - WRPD-001, DDO-001