I fully believe that Mitch’s original design eventually got split up and turned into Bergy and Nix.

(Click/Tap for better quality)

In a similar vein, you have this guy from the 2015 Pitch Bible:

There’s a chance Agent 68 would have appeared in season 3, but I believe he got scrapped and was split into two characters.

His general purpose of “Shady Hinobi Higher up whose name consists only of a title and a number” went to Barbara, Aka Inspector 7 and his design or at least parts of it were eventually made into the Tech Inspector from I’m Mitch Williams, also named Agent Boyd. Just look at the face.