Mafia 107. Fever and Overdose

Does this apply to other redirects as well?

Yes, if a player redirects the checker, then the checker will receive a different result with a different nickname.

Can the ultimate ability also be "duplicated"?

I'd like to say yes, because duplicating the ultimate ability of the Town Sheriff doesn't make much sense, while the Mother's ultimate ability could affect both city locations.
But then I realize that if a Liar gets a victory in the board game in the mid-game, then a double ultimate ability from him could easily turn the game in favor of the Mafia.

So, probably not, I'll add that the ultimate ability cannot be duplicated.