Gosh they are so cute! Two drakes would make a quieter pair? I am really set on call ducks as they are just so adorable!
Jpat is correct, males will still try to mate each other sometimes. I’m not sure how aggressive the drive would be if there weren’t any females around though. I don’t think they would actually hurt each other. My boys chase each other around, but they still get along very well.
And yes they can fly. Mine take flights across the yard quite often, and have flown over the fence, but they come back. (I had one disappear above the tree tops, I watched him fly away. After walking a mile looking for him, I gave up and he returned on his own about an hour later) Their secured area is covered with netting. So you could either keep them confined, or clip a wing.