Is it possible to play with a Guest if you are already registered?

https://www.chess.com/game/live/38915382061 its my lastest game, i thought guest can only play with guest? Or its possible in "Live Chess"?

Idk

He prob made his user like that

Upon looking it seems that matchmaking is broken and you can play guests.

that is definitely a guest they don't have an account

probably post it in the help and support club