Hmm, well in my opinion you would want them separated, because I think aggression tendencies would be very different heads-up in comparison to multiway.

Yes, although HM himself has never separated HU and MWP by displaying the values of aggression (at least I don't remember that there were such stats) if you make a definition for yourself, perhaps it's worth separating. Although my definition defines aggression on the turn, and only HU is allowed on this street , it is possible to actually correctly forbid MWP even on the flop.