Interpretation of This Film -- *SPOILERS*

Rating: 10/10 (29 November 2013)

They weren't twin brothers. The Professor knew *exactly* the secret word to tell how to go get a copy of yourself made: "TESLA".
(1) This film is meant to illuminate the genius of overlooked scientist Nikola Tesla. The film does its best to present us with an extraordinary historical figure whose legacy, in terms of posterity's historical recollections, is less than extraordinary. Tesla cannot be relegated to a mere side-show figure for this film or for its interpretation. A fictitious figure could easily have taken the character-role.
(2) The film seeks to illuminate possible humanist qualities. It doesn't promote such qualities: the characters are too flawed. This is similar to the quantum mechanism of light -- is it a wave, or a particle? In one sense it exists at a captured moment in space, but in another it could be either real or unreal depending on the observer. That is what I mean by "illumination" of the subject matter. Both "illumination" and "illusion" share the same family of Latin roots.
(3) You are left with a verbal cliff-hanger. But the film gives no evidence there could be any more story.
At some point, the Professor went to Tesla for a teleport mechanism, leading to two possibilities: (A) Tesla and the Professor believe the teleport was unsuccessful. Later, The Professor meets his double outside, and they leave. Tesla is left none the wiser.
(B) Similar to (A) except the Professor and his clone return to show Tesla what occurred.
I suggest the latter. Tesla speaks gravely of the mechanism with Danton on the veranda. If Tesla didn't know that he was producing clones, he would have no reason to ward Danton away. This recurring theme of "getting your hands dirty" shows up here. If this was Tesla's own "maiden voyage" becoming acquainted with his machine, he would have no reason to be so reserved.
We don't see who burns down Tesla's shop. Tesla and his assistant climb into their carriage, apparently with a huge, malfunctioning device that had already been paid for. In an inferno, are they going to spend time dismantling a huge apparatus and packing it up? At this point in his life, Tesla was quite used to rebuilding things. I posit that Tesla and his assistant burned down their own shop.
The Professor only has one clone. In contrast, Danton unimaginatively lives out the flaw of the machine so that it becomes his own most tragic flaw. Recall the scene when he is half-drowning himself in the sink while trying to visualize what suffering his wife went through as she drowned in the ropes act, perhaps out of a lingering sense of guilt.
Danton's first instinct at seeing the copy of himself was to shoot himself. The lineage of memories is only kept on with the Danton who survives. One Danton experiences that death, the other does not. It is explicitly stated by Danton that he never knows which Danton will die.
Danton cared more about being in front of the audience than giving the audience any reason to applaud. He cared more about stealing his opponent's technique than about the memory of his own wife. It's enough to him that one "part" of him is going through his wife's torture, as long as the other "part" of him is basking in glory.
The Professor's wife is treated poorly and the mistress was treated off-handedly. Both of those women took a secondary role to performance. Considering each Professor had so much to gain by sticking with his own woman, the only one real reason to switching was to make it believable. The women could be left to hang and to run, as long as they didn't ruin the act.
Cutter himself is always in the dark. He doesn't know enough to make a moral decision, but he acts anyway. He gets one man killed while working for another man who gets 100 killed.
There is no actually presented moralistic ideal. The wife may have been innocent, and may have been conscientious, but she left behind a child and a man who (at least every other day) genuinely loved her. She's the moral maximum in this story, but a relative maximum at best.
At the end of the film, take stock: (i) One of the two Professors is dead.
(ii) The Danton who survived a slew of clonings is dead.
(iii) The remaining Professor has his daughter back.
The only possible continuation of the story would be that Danton decided to allow one of his clones to live. The movie presents no evidence of such. If we say "there is still be another Danton", then we're just making things up.
I would like to allude to the experimental hypothesis known as "Schroedinger's Cat". As soon as you open the box, you "collapse" the light's function to either a particle or a wave. Until that point, here is a mysterious existence wherein the cat is both alive and dead at the same time. The Professor is the one who opened the box and accepted fate for better or for worse.
The film is largely an allegory of the failures and the successes of quantum physics, and a toast to the magic and mystery of the designs and discoveries of Nikola Tesla. Those are its primary features. So things like morals also get tossed into Schroedinger's box. But morals are absolute things. We don't say that ambivalent morals are still moral. Morals are treated as valid only when they are absolute and guarded. A person with changing or ambiguous morals is said to act either ethically or unethically, but their morals are no longer validated. And even ethics are considered to be culturally relative.
The tease at the end with no further evidence is the film's send-off, its own lack of a "prestige", admission that the story is truly told in full.