If you want to run two or more X11 sessions on the same computer at the same time, you can do the following:
startx -- :1 to start a second X11 session
Note:
8:23:respawn:/sbin/getty 38400 tty8/etc/inittab file.
startx -- :2 to start a third X11 session etc.
Comments
Second monitor
How to direct the second X11-session to another display-device (second monitor on my laptop)?
Second monitor
Hm, not sure. I think you need Xinerama for this (do a Google search, please).
Uwe.
the screen command
the screen command particularly xorg,conf