My niece gave me her two laying hens when she moved to a house without the space to keep them. She mentioned that one hen used to peck the other and gave me a spray that was supposed to inhibit this behaviour. For the first couple of days they seemed all right and then the pecking hen increased its pecking so that the other hen had bald patches all over its body.
I then installed a wire netting barrier between the two with water and food in each plus laying space. The hen that had been sujecte3d to the pecking then became absolutely bereft pacing up and down its side of the wire fence clucking and jumping up and down obviously distressed at being parted from the other hen. I don’t know what else I could have done, perhaps someone here does.