i will say it again, curlyfatbottom.
just because it works for you, doesn't mean it will work for everyone.
that means, that just because you can have males live together, doesn't mean anyone who's new to this should. i've kept bettas for 2 years. all of mine, except my CT and my new Veil, can live in plain sight of each other with little to no flaring.
does this mean i'm gonna put them in a tank together and force them to live together?
my boys and girls are happiest in their own tanks. with their own territories. with the ability to hide in their plants or caves from each other whenever they feel stressed.
clamped fins and inactivity, like you say your males show, are signs of them being stressed.
which means, in simple terms they aren't happy
stressed fish get sick easier than happy, not-stressed fish. it's a proven fact that stress lowers their immune systems. i'd rather my fish live in their own, unique tanks, than shove them together because i can. :I