Spoilers - why is Angier confused about...
After Angier is shot by the surviving Borden twin, and they are talking about making sacrifices, Borden says that Angier has never made any sacrifices. Angier replies, saying that (with regards to his version of the vanishing man trick) he never knew whether he would be the drowning man or the prestige (successfully "transported", bowing to the audience, etc).
However, when he tests Tesla's finished machine, he deliberately places the gun some distance away from the machine, right where he ends up being "teleported". So, it has always appeared to me that Tesla and Angier are certain that the man who steps into the machine is teleported, while the "clone" or "copy" is created in the exact same spot inside the machine. Therefore, the clone is drowned (when the trapdoor opens), and the original Angier always survives.
Am I wrong? Did I miss anything?