I think it is more a 'top dog' thing - he is now at the age where he wants to be the leader of the pack, and is scent marking his territory, especially as he has bitches in his pack. You can get sprays for putting them off weeing in certain places, but I have never known them work 100%. Depends on the age/mentality of the other male, if he is happy to be second in command then the behaviour should stop naturally, but if he is going to stand up for his rights, then you might have some problems. Castration will help, but in the meantime keep a spray water bottle handy and spray the dog if you see him go to lift his leg.