I wasn’t able to reproduce it, but I was able to record a little video: sometimes the editor has two cursors:
After recording this I clicked on another tab that was already open and there were two cursors.
I clicked on another tab that was already open, and there were two cursors.
I clicked on another tab that was already open, and there was one cursor. After this the second cursor didn’t come back.
This is not the first time I see two cursors in the beta editor.