First of all,
! It's nice to see another new member!
swtangel321 is right about the ratio of roosters to hens. I'm actually surprised that the hens and roosters you have right now are living in harmony.
Roosters can be very domineering, and to prove their dominance over the other roosters, they will mate the hens in the other roosters' presence. It's kind of like "laying a claim" to the hens: "She's my hen, see? Go get your own."
If you have a lot of roosters and only a few hens, the hens will often be over-mated as the roosters struggle to assert dominance. This can be very traumatic for the hens. They can be injured and lose a lot of the feathers on their backs from too much mating. They can also be "gang-raped" to death, or become injured trying to escape or run away from the roosters.
I suggest choosing the rooster that seems like the best "flock protector" to live with your hens, and put the other roosters in their own, separate, bachelor pad.