Yes. If there is one thing that's extremely difficult to avoid if you keep chickens long enough, it's having to kill one (either because of disease, injury, predator attack, or hen/rooster ratios that cause harm). If you re-home a rooster, it's likely whomever takes them will kill them (free meat), too; not always (we rescued someone's "extra" roo, once), but often.
"Extra" roos are just very difficult to permanently find homes for because of their inherent nature; they do best with 9-12 hens per 1 rooster. If you have multiple roos and less hens per roo than that, you're setting up an environmental where the roos will not only persistently fight each other, but will run the hens ragged. This results in significant stress on the whole flock, which reduces vitality. You end up with hens not laying, injuries, and due to stress, illness. If that drags on, you end up with birds dying prematurely or a disease outbreak bad enough to kill them all. As
@sourland said, the roos can kill the hens, either by direct, constant and repeated pursuit and mounting and/or not allowing the hens to eat or even drink enough because they're always being chased.