Possible To Run Two Desktops

[Kenneth Loafman]

Folks,

For testing purposes I'd like to be able to run two, or more displays (X
displays, not monitors), ideally Gnome, KDE, Xfce, and be able to switch
between them with the Alt-Ctl-F7, Alt-Ctl-F8, ... sequence.

I would also like for these to be accessible as 'vncviewer foo:0',
'vncviewer foo:1', ... and so on.

Is this possible?  If so, could someone point me to some detail on how
to set this up?

...Thanks,
...Ken