I have a slew of roosters (and a slew is more than ten, in my case) which do not fight. One did, and he was culled with a shovel. Mean, mean, mean and destructive bantam cochin, of all birds!
They spar for dominance and settle down once that is established. Everybody's flock is different, but having two roos is not necessarily a death sentence for either of 'em. Especially if they have been raised with each other.
I have added roosters (well, chicks which turned into roosters, I didn't specifically ADD roosters!!!!) which grew up in the flock with older birds and even they learned their place in the pecking order without mayhem. Mostly they fluff up their hackle feathers and stare each other down. Occasionally there is some pecking and feather loss, but nothing serious at all.
Good luck, whatever you decide!