Sometimes fish just don't read the book and you get away with things you normally wouldn't. I'm not saying you HAVE to separate them but also don't be surprised if this backfires on you big time. The males not being aggressive make me think that they are either very old and tired or not properly being fed and are not as healthy as they could be. Taking all this into consideration, they also just might be ok and ok with each other ( a rarity for sure
). Obviously the choice is yours but as I said, be prepared.
The good news is that with that size tank, you may get lucky and just suffer fin damage, which is healable. Hopefully, that's the worse case scenario.
Lots of luck on this