Three different things could happen. I cannot tell you which of the three will happen.
1. They will fight and reach an accommodation. One will become dominant and the other becomes his able assistant in protecting the flock. They actually work pretty well as a team. The fight will probably be pretty vicious.
2. They will fight and one will kill the other if they are so close in spirit that one cannot get a clear advantage and neither is willing to accept the second in command position.
3. If one rooster is extremely dominant, he may kill the weaker one just because he is so weak. It is as if he is saying that he does not want the weak roosters genetics in his flock. The second in command gets his fair share of the girls, especially if there is plenty of room for him to get away from the dominant rooster.
Actually 2 roosters for 14 hens is not that bad a ratio, especially with Cochin. Plenty of breeders have a one hen to one rooster ratio in the breeding pens and do not have a problem with barebacked hens. Some people have one rooster with 18 hens and still have some barbacked hens. There are a lot of factors that go into whether or not your hens are barebacked. The ratio can be one of the factors, but it is a very tiny factor in importance.
The reason I say especially with Cochin is that some breeds, Cochin and Orpington specifically, have such thick feathers that the rooster sometimes has trouble finding the target. Some people trim or pluck the feathers in the appropriate regions to help with fertility with these breeds. I'm not saying the rooster always has these problems, but it happens often enough that vent trimming has become a recognized practice with certain breeders and certain breeds.
