I don't know if you've seen this or how much of this you know already. It might help explain some of what yo are seeing.
Typical mating behavior between mature consenting adults.
The rooster dances for a specific hen. He lowers one wing and sort of circles her. This signals his intent.
The hen squats. This gets her body onto the ground so the rooster’s weight goes into the ground through her entire body and not just her legs. That way she can support a much heavier rooster without hurting her joints.
The rooster hops on and grabs the back of her head. The head grab helps him get in the right position to hit the target and helps him to keep his balance, but its major purpose is to tell the hen to raise her tail out of the way to expose the target. A mating will not be successful if she does not raise her tail and expose the target. The head grab is necessary.
The rooster touches vents and hops off. This may be over in the blink of an eye or it may take a few seconds. But when this is over the rooster’s part is done.
The hen then stands up, fluffs up, and shakes. This fluffy shake gets the sperm into a special container inside the hen near where the egg starts its internal journey through her internal egg making factory.
You do not have mature consenting adults, you have unruly immature adolescents. At that age mating behavior is not about sex, it is about dominance. The one on bottom is accepting the dominance of the one on top, either by choice or by force. In your case it is by force because that pullet is not consenting. If they are only going after her it is possible she is the dominant pullet, not the weakest and is their biggest threat. Or she may be the weakest, I don't know. Still they are after her.
Typically my pullets start to act like adults about the time they start to lay. It is not purely tied to age. There is no set age for boys to grow out of this hormone-driven stage either. I've had a very few manage that at 5 months, I've had some not manage until about a full year old. Typical is closer to seven months but not all are typical.
Once the males and females both reach their levels of maturity they generally know how to behave, but you probably know some 50 year old men and women that never left adolescence. Same thing can happen to some chickens. But once they mature they usually become a pretty laid back flock. Usually.
Sometimes having competition can stir a cockerel into more aggressive behavior. Eating one might be a reasonable strategy. It might not help but he'd be delicious. Which one? Get personal and feel them up, see which has the best meat. That's your breeder. Sometimes the feathers mask which one has the best meat, that's why feeling is best. But removing one might not help at all.
What do I do when I'm in something close to your situation. My conditions are a little different, I generally have one mature rooster, 6 to 8 mature hens, and maybe 15 to 20 pullets and 15 to 20 cockerels, not all the same age. I generally just let it go. No one is really getting injured. Usually my pullets hang with the boys, just run away when the boys get amorous. Often the boys will chase them down, grab their head to control them, and mate with them. Sometimes the girls get away but not that often. Occasionally some pullets hang in the coop, often on the roosts, to stay away from the boys. I have food and water inside and out so they don't starve or get thirsty. Your weather is a bit cold right now though so water may be a challenge.
I hardly ever see any gang rape or anything like that. It's rowdy, it's rough, but no one is getting hurt. About once every three or four years though it gets too rowdy even for me. So I lock a dozen or so of the older boys in their own separate grow-out coop away from the flock until butcher age.
This behavior generally starts with mine when the boys are about 15 to 16 weeks old, yours are late starters. At about 16 weeks I start butchering the ones I know I don't want to become my flock master. Breed the ones you want to eat and eat the ones you don't want to eat. Usually it is pretty to select the first and by 23 weeks I'm usually down to two or three left. That's when I usually make my final decision. I may not always guess right regarding behaviors, but it's usually not a horrible choice. But you only have two to choose from. That may be easy, it may not.
I see your options as letting it go and see what happens, but observe to see if any are getting hurt. Eat one now and see if that changed anything, or lock one or both boys separately for a month or two or maybe until a few pullets are laying and then try again. I would not fault you for any of them. I would not eat both because they are acting like typical teenagers and you do want to eventually breed them.