"1920: Complete set of 13 stamps with hand overprints "P.P.C." (Postes Polonaise Constantinopole), the 2,50 M with double overprint. All stamps on nice cut-outs with blue cancellations "Poczta Polska Konstantynopol" in very good condition. The double overprint on the 2,5 M is the ONLY KNOWN COPY. Signed W. Rachmanow, certificate Z. Korszen. Very Rare." (Image)