Roosters/cockerels will do that, especially if there are hens/pullets around. It's all part of the pecking order. If you free range, you have a better chance of harmony w/two roosters. Ina contained run setting...maybe or maybe not - really depends on the personalities of the birds. As long as there's no blood, you might let it go and wait to see if it eases up. When/if it start getting really rough (blood letting), then you're gonna' have to choose or begin using two separate pens - each with their own pullets perhaps.