Oh, Starfleet captains can be so cruel.

Surely they had knowledge of Thomas Riker and the way he was duplicated. If only Janeway would have studied the historical documents, she could have saved Tuvix and unmerged their combined genome.

If Starfleet had the ability to duplicate that freak transporter accident at will, do you honestly think Section 31 wouldn't do that to their agents before sending them on a dangerous mission and put the original in stasis until they knew whether the duplicate had died or not?

Also, someone's already asked that here. If you duplicated Tuvix, you have exactly the same ethical dilemma as to whether to murder the new Tuvix (I can't in good conscience call that one the Twovix thanks to the brilliant LD episode, but maybe I could get away grammatically with Toovix?).

In fact, that would be even worse. "Sorry guy, we created you in a transporter specifically so we could murder you and bring back the originals...". At least the original Tuvix was an accident. Creating a sentient being specifically to murder it is... well, it's something Archer would do, come to think about it. RIP Sim.
- How dare you make me question my personal ethics and having empathy for freaks of nature. Next, you'll be telling me that Janeway and Paris should have stayed lizard creatures. They had a fresh spawn of children that will die in the wilderness now. All life is sacred!
- Why not put Tuvix in the pattern buffer, copy his pattern to storage, separate one copy of the pattern into Tuvok and Neelix, then transfer the Tuvix pattern back before rematerializing him thus saving all 3?
Oh yeah, that’s exactly what we need, a machine that makes more Neelixes.

And as for Tuvix, he shouldn’t have mouthed off like that!

I'm having SevTrek flashbacks.