NeXT ran a Mach 2.0 variant. I forget which Mach features were absent, but NeXT unmistakeably ran 2.0

The BSD stuff was kind of bolted on. Very uneasy marriage there.

At one point DEC had a 2 Mach task system that could run VMS processes, but I'm pretty sure that was Mach 3.0 based.

That is to say, Mach 2.0 wasn't as advanced in portability, and the "portability" targeted was different.