Growing up, my family always had at least 3 boxers (one for me, my mom and my sister, LOL, my dad and brother were mostly spectators in the crazy boxer house) and 2 were always males. For the most part, there were no problems, but if a female down the road or something went into heat, the boys would sometimes fight, even though they were both neutered. And, right now I have 2 male fosters, Bosco and Bain. They get along fine, though it is obvious that Bosco is the alpha of the two. They don't compete or fight over my unaltered female, Roxy, actually, everybody is getting along fantastically! Which was kinda a surprise to me, I thought I would have some problems, but I've had Bosco for about 2 1/2 months, and I've had Bain for about 3 weeks and (knock on wood) there haven't been any issues. Good luck with your decision and upcoming new baby!!