Its not unknown.... I sold a group to a collector in Italy, 6 months later Nieman sold it... somewhere along the line the only photo of the guy had been removed, 20 "combat photos added" the EK1 exchanged, the CCBT clasp added (doc was there), Schirmmütze added, sword added......
Not sure if it was the collector, a guy in between or the dealer......
I would give the PLM owner a chance to buy it back at market value, or get one in the same condition and pay the postage to exchange them. That and the money for a case of good beer.