1945 MARIBOR, Base stamp error

I recently got a stamp with an interesting error...

1945 Maribor provisional issue, No. 8 with missing "1" in "12". Signed Ercegovič.

Missing "1" and some red paint inside "2" suggest that there was some dirt on the cliché during the printing. This mistake is unknown to me. I think it is an occasional error fixed by cleaning up the cliché as soon as it was noticed.

1945 MARIBOR, Partial & reverse overprint

Although it is most likely that the entire margin of one sheet was folded, so all ten stamps from the right edge were partially overprinted on reverse, this is the only piece I have seen so far...

1945 Maribor provisional issue, 15 pf (Mi. 9) partial overprint and overprint on reverse due to paper fold. Attractive and very rare.