[CSpaced]

There are two ways you can activate the governor, either by throttle stick position or a switch. However the governor will only turn on when at 70% or more of the set head speed. In other words, if you are just spooling up and turn the governor on it will not instantly speed up the head until you have reached 70% of the set head speed by yourself.

I am assuming you are using a switch? In which case if you are turning it on in flight and on one helicopter it reacts instantly and on the other it doesnt, assuming the GV-1's are setup the same, then I would suggest that one helicopter has a higher head speed than the other during normal flight when the GV-1 is turned off (the one that is reacting quicker).

I would go back to the two and compare settings, check that you have the correct gear ratio, look at what you have the head speeds set to etc.