Confusing usernames when joining a circle asking nickname

What's happening?

I ve created a circle today to explore pb about issue applications/hubl#906 . I was able to create that circle https://lepool.hubl.world/circle/@https%3A//api.lepool.hubl.world/circles/149/@

When joining back the circle it asked me to put a nickname, I did so.

Doing it several times, circle asked me again to put a nickname and I realize I can have a different nickname each time I go back in the circle.

Quite confusing for users if we authorize with that behavior.

Steps to reproduce

How one can reproduce the issue - this is very important

1. Step 1 Go to the circle named ztest on hubl,fill a nickname then chat
2. Step 2 Go again to the circle named ztest on hubl,fill a nickname then chat
3. Step 3 see you can have several nicknames

Relevant logs and/or screenshots

After this if I try to @mention someone it propose to me all the nickname users that are within the circle.

Issue related: applications/hubl#906