Comment 3 for bug 1859526

Yes, after 18.04, it was no longer possible to run two independent desktop sessions, even if you have a single GPU supporting multiple screens. It boggles my mind why this incredibly useful capability was allowed to just die. You can still gang the two screens together with the panel running on one screen and the window manager running across both, but you cannot control them independently; i.e., if you switch desktops both screens change rather than just the one you would like.