What do you mean by "for male ducks"? If those are the only boys you have, I think they'll be fine together. I kept just two boys alone and they were the best of friends, two peas in a pod. I didn't notice mine personally trying to mate my chickens, but they're bantam ducks and all of my chicken...
We'll have to get through the "sexing call ducks" thing together. Mine is 8 weeks (just bought her two days ago) and I'm realllly hoping Pippa's a girl.