it depends. If you are servicing for others for O2 use, then you damn well better be using the poseidon greases since the manual says specifically not to use christolube because it isn't rated for high pressure use. If you're doing O2 regs, then you need the HP grease and the normal pressure oxygen grease. If doing non-o2, you need the normal oxygen grease and the regular grease, so only 2 depending on which one you're working with.
If you are servicing for yourself, I see no reason not to just use christolube or tribolube for everything if doing oxygen service. I use dow-111 on all of my second stages regardless of oxygen service or not, and I use dow-111 on all of my non-o2 first stages.
Note that Poseidon says specifically that no regs that were not originally machined for oxygen use are able to be oxygen cleaned, and any regulator that has ever been serviced with normal grease can no longer be properly cleaned for oxygen service
