Using multiple X-Sessions allows a user to have open more than just one instance of XFree, so multiple desktop environments can be used at a time.

startx . :<terminal name>

terminal name is simply which terminal X should start on. By default it starts on

0:0. If you want two open, you may want it open on 0:1, which can be run by:

startx . :1

The resulting desktops will exist on F7 - F12.