I just picked up a set of sheets of the Overrun Countries set.
I'm familiar with the reversed color errors, the "KORPA" error, and various double impressions that Scott lists. However, in the preface to the set, Scott mentions numerous other varieties/anomalies NOT listed by Scott.
Looking through the sheets, the Belgium (Scott #914) stamp appears to have WAAAAAAY more anomalies than any of the other stamps. Is that accurate, or do I have a wonky sheet?
I don't think that any of them are the Scott-listed double impression, but there's definitely stuff going on. See image below of the most dramatic of the stamps in the sheet.
(Click on the image below to enlarge it. It's ginormous.)