chicks fighting

[henroo]

Hello everyone...so here's my problem... one of my hens hatched 6 chicks... of the 6 there was 4 cockerel and 2 pullet.. due to an accident one of the cockerel died and a predator i think it was a cat or dog took another cockerel...now of the remaining 4 there are 2 cockerels...3 to 4 days ago their mother weaned them.. she pecks them etc but she let them under her at night... she even started to lay... the chicks are 2 months all and this morning i've started to notice some serious fights between the 4 chicks but mainly the 2 cockerels... one has a swollen eye... right now i've seperated one of them but he is crying his lungs out for me to let him out of the coop...what do i do..?? The little one get to free range all day. It's the first time i've closed one of them in the coop...