huge, unsolved debates over morality

One shouldn't confuse there being a huge debate over something with the problem being unsolved, far less unsolvable (look at the debate over free will or worse p-zombies). I have actually solved the problem of the moral value of animals to my satisfaction (my solution could be wrong, of course). As for the problem of dealing with peoples having multiple copies this really seems like the problem of reducing "magical reality fluid" which while hard seems like it should be possible.

also in math, it might be possible to generalize things, but not necessarily, and not always uniquely

Well, yes. But in general if you're trying to elucidate some concept in your moral reasoning you should ask yourself the specific reason why you care about that specific concept until you reach concepts that looks like they should have canonical reductions, then you reduce them. If in doing so you end up with multiple possible reductions that probably mean you didn't go deep enough and should be asking why you care about that specific concept some more so that you can pinpoint the reduction you are actually interested in. If after all that you're still left with multiple possible reductions for a certain concept, that you appear to value terminally, and not for any other reasons, then you should still be able to judge between possible reductions using the other things you care about: elegance, tractability, etc. (though if you end up in this situation it probably means you made an error somewhere...)

generalize n-th differentials over real numbers

I'm not sure what you're referring to here...

Also, looking at the possibilities you enumerate again, 3 appear incoherent. Contradictions are for logical systems, if you have a component of your utility function which is monotone increasing in the quantity of blue in the universe and another component which is monotone decreasing in the quantity of blue in the universe, they partially or totally cancel one another but that doesn't result in a contradiction.