Keeping them together, preferrably in a large paddock, without mares should help, as they will be able to establish their pecking order properly and they wont have girls to fight over. I would perhaps later introduce mares, depending on their relationship, once they were quite established together. They will likely still indulge in 'horse play' which can look quite scary to the uninitiated, but it's less likely to be more than a game.
While I agree with others who have said the recently gelded one could settle down when the hormones are no longer present, this depends on age and previous learned behaviour. I'm presuming the one gelded as a yearling was gelded youngest? This is still old enough for the horse to have had lots of experience playing happy stallions - even if he was too young to take it far. As with getting dogs done when they're already grown, depending on the animal's previous behaviour & experience, there may be little or no behavioural changes with The Cut.