As a WHM, I'd prefer to heal alongside a competent scholar rather than a 2nd competent whm. When I'm in party with another WHM, we're constantly overlapping heals. We both toss a Cure I or II on a dps that derped and one of us wastes a cast. Or we both Cure II the tank and overheal him. When I'm in party with WHM I find myself watching what the WHM is casting half of the time. And I usually end up just spamming stoneskin on the tank rather than cast any cures because half of them would end up as overheals.