As Bobbi explained, it's perfectly normal. They are coming into adolescence and the hormones are running wild. They are going to try to dominate each other and any females, especially pullets their own age. At some point they will try to dominate older hens but Dad will have something to say about the young boys bothering his hens. It's likely to get very active and messy down there. As someone said, watching this phase is often not for the faint of heart.
Will they fight to the death? Maybe, maybe not. If you have enough room they may work everything out and be able to live together peacefully, but that will probably take a lot of room. There are always exceptions but the normal sequence of events is that the boys squabble in the flock among themselves and work out a hierarchy of who's in charge between them. Eventually Dad kicks them out of the flock and they leave home territory to set up their own territory. If a cockerel can eventually convince some females to join him he has his own flock. Or when one matures enough he may go back and challenge Dad for flock supremacy and try to take over his flock.
Very few of us have enough room for this to play out this way so it can get really messy. Since they can't be kicked out of the flock because of lack of space there are a lot more fights (and sometimes more serious fights) in our flocks than there would be in the wild. Still, they often reach an accommodation on dominance and rank so they can work together with the flock. How much room you have is very important in this. The more room you have the better. The tighter they are packed the higher the risk.
I raise cockerels to butcher age (18 to 23 weeks) with my flock all the time. I have a fair amount of room but it is not unlimited. Most of the time I see a lot of squabbling between the cockerels but no serious damage. When the boys start harassing his hens the mature rooster objects and may chase them some but seldom harms them. Some mature roosters are more serious about that chasing and trying to catch them than others, but there is seldom any real harm done to the cockerels from him.
A few years back I had 18 cockerels about the age of yours, hatched together and raised together. At about 15 weeks one developed a real hatred of another. He was constantly chasing and trying to harm that cockerel. I thought they had enough room to make it to butcher age but I was wrong, eventually he did kill him. After he killed that one specific cockerel he got along fine with the other 16 until butcher age. That's the only time I've seen it that serious but the individual personalities of your cockerels (and Dad) has a lot to do with what will happen. With living animals you just don't get guarantees.
What will happen with yours? Obviously I don't know. If you have enough room (and how much room you need will vary flock to flock) they may work out an accommodation. Or chickens may die. Unless you have pretty much unlimited room I suggest one of two things. Either get rid of most of the males or set up a bachelor pad where the males can live together without any females to fight over. Bachelor pads are usually pretty peaceful though at 4 months they will determine a pecking order.
Good luck!
My other chickens leave little comb pecks alone, but I'm not sure if yours will, so monitor them. I do, however, take them out and gently clean it with water and a cotton swab then let it heal itself.
