The Fire of Hephaistos gives a brief mention of the bronze head of Caracalla that was removed from the Sebasteion at Bubon in Turkey (and others appear in the catalogue). The same head is mentioned in Gill and Chippindale, "Material consequences of contemporary classical collecting", AJA 104 (2000).
And now this head appears in the Fordham University Collection inv. 7.068: "it has been suggested that the Fordham example may have belonged to a large statue group of Roman emperors from a Sebasteion in the city of Bubon". Indeed it has been suggested that the head fits the headless statue in Houston Museum of Fine Arts (also apparently one of the Bubon statues).
The curatorial team at Fordham may be unaware of the issues surrounding Bubon. But I hope that one of them will do the honourable thing and contact the cultural attache at the Turkish Embassy.