I can’t say I’ve ever personally had that problem, but others who have will often take a pool noodle, slice it open the long way, and place it over top of the hangers. You could also:
- Place a tension rod over the closet rod which would prevent the hangers from bouncing off.
- Attach a bungee cord from one end to the other end of the hangers.
- If you have an uppershelf, stuff a pillow between the rod and the shelf.
Those are just a few ideas.