It would still be okay to kill one before divergence, I'm just saying unless the person is special there is no reason to want more than one of them, just like you don't indescriminately want more children.
Even if you could somehow tell how "special" a person will be in the future you would still be left with a very twisted argument without a basis in reality or ethics. How do you know a stupid person won't save a genius baby from death sometime during his life? I don't know where you're from, but in most societies it is considered inethical to make a choice whether to kill or spare someone based on the value you believe they will serve society in the future. Even if you knew that someone wouldn't go on to achieve greatness, most would frown on murdering them.
That you have somehow reduced the equation down to an economic one is especially telling, and I simply don't believe you've thought the implications through. History shows this line of thinking to be an especially treacherous road leading to a place where even materialists would not want to go.
I say they would have to diverge to do anything useful, because with our perfect duplicater the only novel thing they can produce is information. If they don't diverge, they just produce the same information, which isn't useful.
Exactly my point. And once they diverge, they are two different people. So the concept of killing one of them for the sole purpose of keeping them from diverging is a bit of a problem. If you let them both live, you are left with a different dilemma, that you now have two people who both claim equal rights to the same life. Reason enough to take the bus instead, in my opinion.
To the actual matter, rather than ethics and economics (both of which I feel much less certain about), I pose the question to you: Suppose we take our duplicates, and randomly place them in a room. The clones are then left alone, and they use a random process to decide who should open the door. No one has kept track of which one has the original atoms. What possible test could distinguish between them?
First, remember that the two people in your scenario are necessarily divergent if only one of them walks outside of the room. Second, you are confusing the concepts of identification and distinguishing. Identification of which is the original and which is the clone is a separate issue from distinguishing them from each other. Distinguishing one from the other is trivial: one will be outside the room, and the other inside the room.
If you are asking how we can tell which is which (identification), we can do that the same way we can identify identical twins: ask them. In fact, there is little difference between the scenario you described and a pair of identical twins whose past is unknown. Let's pretend for a moment that they might have reason to lie or cannot identify themselves, and there is no way at all to tell them apart. What conclusions do you draw from that fact? Think carefully.
...Why should we say they are an original and a clone, if that makes no meaningful difference?
The question of identifying which is the original and the clone is only important from the standpoint of knowing who owns their life. The fact that it's difficult if not impossible to actually tell only illustrates one of my points of why folks might not want to "teleport" in this manner. However, this question does not have any bearing on the ethical implications of killing one of them since everyone has agreed that two divergent people are two separate and unique people. Just as identical twins are unique people even if you can't tell them apart (indeed even if they couldn't identify themselves).
Why should we suppose that a difference exists between them? And if no differnce exists between them, why do you suppose "you" doesn't exist in both of them?
If you are asking why we should distinguish between the two, the answer is simple: because they are different, even if we cannot identify which is the original and which is the clone. They are two different people, and therefore will contribute differently to the world in the future, so it makes a huge difference both to them and to the world. One of them might go on to cure cancer or save the life of a baby who will grow up to cure cancer, and the other might not.
So again, let's say that we cannot tell the clone from the original (or identify two identical twins), what conclusions exactly would you draw from that fact to further your argument?
-Bri