I recently stumbled upon this curious set of obviously fake Labuan overprint offered in eBay. To be fair to the seller though, he did put a lot of question marks on the caption and quoted “ex Jim Czyl” (or James C. Czyl), a leading authority and researcher in Cinderella stamps.
The first set was a red-maroon Labuan overprint on some random Japan stamps from the 1948-49 issue.
What’s more exciting is that the Labuan overprint was also found on various US stamps, offered by the same seller. This time the postmarks seems to be on top of the overprint.
I haven’t seen this overprint before and I’m not really sure what to make of it.