I see your point. But I don't see a real problem, players have more flexibility that in reality but one turn penalization and fatigue penalization are enough, I think. In the games I played I didn't see an irregular use of double shot.
In real life, double shooting overheat guns and is more dangerous and harder to accomplish in combat so it was not usual, mainly only as first shot. I read that Royal Navy, in more modern times that what we play, refused some kind of guns just because they couldn't be doubleshoted so I think double shooting is not totally unusual in combat.