Sure, they had doubles, but why would Hitler’s body double be in tiny Nussdorf am Inn after Hitler was supposed to have killed himself? To fool one American POW? More likely, the body double was sent to the bunker so Hitler could escape. The Nazis planned Hitler’s escape the way the Secret Service plans transferring POTUS to a bunker. They had a detailed plan, and they followed it, complete with fake forensic evidence like X-Rays and dental records. There were enough dead corpses around to find one about Hitler’s build and say it was him. All the Nazi loyalists said Hitler killed himself, and they all told the exact same story, which they rehearsed to hide their fuhrer.
At that point, there’s no reason not to put a bullet in AH’s double.