When a non owner instance notice a conflict it should request a repair

In theory, the main instance should also eventually notice a conflict locally and repair the other instances but in some rare case and possibly help with some bug in a custom replication controller you might end up having to wait for a long time for the owner to have enough information to notice the conflict. It does not harm to have an instance pro-actively ask for a repair, at worst it will simply receive 2 repair messages instead of one.

This "Force repair" feature should also probably be exposed in the "Troubleshooting" section, next to "Force push" to allow admin to easily request it in case of bug.