If I refunded a Uplay game on steam, the game stays on Uplay.

huh i though third party game refunds weren't a thing on steam

Didn't know you can refund stuff with 3d party connectivity like that ...

Also I don't see a reason why your Uplay version wouldn't work I'd you rebuy the game

It actually happened to me it would seem, with Rayman Legends, I refunded it cuz I thought I got Rayman Origins but bought the other one by accident, so refunded it, so I was left with the Legends in my account, but have no fear, that game is bound to Steam, so I can't download/play it cuz when I click it it just takes me to the Steam store page, despite remaining in my uplay library.

Yeah it will work. That is considered not fair, though. Whether you want to do it is up to you, I personally would not. If I want to buy, I buy legally. If I want to do that thing, I'd rather pirate it altogether.

I'm not saying it's wrong, it's just my preference.