I know lady who does this, she has a ton of birds in cage and all of them get along.When no females available for them mate with aren’t around they become so laid with one another.Its also easier to introduce one.I recently bought a rooster from a bachelor flock and he does so well with my little bantam roo who was getting bullied by our Jersey giant rooster who I actually traded the lady out for.When he first got with the other roosters he fought em all and immediately took over, I personally think it was because he was fresh away from the girls.But, this is also not the greatest idea.You could contract so many disease from random birds.Thats so many birds coming from so many different places, that could be a big issue, it would involve a huge amount of biosecuriry.