I got a call from a friend asking where he could get a genuine Murray
hacr breaker. He had another friend help him with wiring for a heat
pump and the friend had put a GE hacr breaker in his Murray panel.
The electrical inspector insisted he change out the GE breaker for one
made by Murray.

I have not seen the panel, so there could be a good reason. But is
there anything in the NEC that requires breakers in a panel to be made
by the same manufacturer of the panel?

Dan