Technically a notification could be if a instance using the same name pops up, but that wouldn’t be that simple. I don’t think its that tedious to check the list every once in a while.

As to the design I had an idea. It could be a list of instances using the name and at the top it has a join all button. Then instance has its own join button.

I’ve seen those a lot lately on 1337x, but they should still be more common.