From Diablo Wiki
Bertram Thistwhistle, "The Silent Bandit", is a Superunique Human that appears in the Ransacked Dwelling in the Westmarch Commons in Act V in the context of the Home Invasion event. Another Superunique villain, Virgil Cutthroat, appears during this event. He looks identical to Bertram Thistwhistle. Maybe this is his twin brother who followed the same despicable path.