Serama Pair with Full Size Pullets

[ShyTown]

Hello!
We have 1 Sermeya roo with 4 Sermeya hens in the same coop with 5 large hens and 1 enormous lavender Orrington roo.
The little roo never tries to breed the big hens, however the big roo has tried to breed the little hens several times. I stop him if I catch him.
They all live and love each other. The big roo penetrated a Sermeya hen and it stretched her vent out really bad. I though she would die but no! She follows him more than the little roo now.
I hope this info helps
-SD

Wait...but I read that chickens don't have a penis. How did he damage her? Do you have any ducks by chance? This is the only reason I know this as, I had to get rid of my ducks because the male was attempting to mate with my hens and in research found that roos don't have a penis but ducks do. Which can cause major damage.