
We have almost always had two males living together (hounds) - in fact our first two were males, almost a year apart in age. BUT my main breed was a socialable breed, a hound used to living together without the spats sometimes seen with Terriers. Yes they had the occasional disagreement, especially after our third joined us, a female

I did have just the one boy, kept from an all-male litter, who by the time he hjit around 18 months, started challenging his uncle. This youngster had never been used at stud, but his uncle had, and once challenged, did react. I tried all I could think of to get them to sort out their differences, including shutting them in our outside pen (with a hose to hand). They lay together at the gate, nose to nose without any sign of a fight. Once back indoors, later on, it all kicked off again. By then, and the fights were getting increasingly more serious (blood), I'd had enough and found the younger boy a super home, with his own girls. I co-owned him at first but later on, went to check on him and found he was happy as larry, acknowledged us but returned to what he'd been doing. So eventually I signed him over to his new owner. And peace returned to our small pack.
It is possible to have two males together - in fact from my experience, and this is just with my hound-breed, the males would be more inclined to have spats if we had a bitch in season but then it was allover. Males generally fight to mate - bitches to survive.
Of course the acknowledge best combination is male and female. But the female would have to be spayed. How well this might, or might not work would depend on you correcting the puppy if he gets too much for your older dog. Adults tend not to attack puppies but if he doesn't see you in charge, he might - sharp teeth hurt! You may not be able to leave them together, unsupervised, at first.