Add new display manager instance to another tty?

[nchase]

How do you start up a new and separate display manager instance on another tty (ctrl + alt + [f1-f7])?

[RAOF]

This is exactly what fast user switching does. Each user has their own X server running on a different TTY (except they use 7, 8, 9, etc). I'm not sure what happens if you fast-user-switch and login as yourself again; I presume it works correctly.