Comment 8 for bug 903194

LightDM currently assigns each seat a different VT and switches to that VT when starting X. This is why hitting Ctrl-Alt-F7 and Ctrl-Alt-F8 switch between the two seats.

The proper way to handle multiseat is to have only the primary seat switch to a VT, then have all other seats share that VT with the -sharevts argument. LightDM doesn't currently support this, but I have some changes to LightDM in progress to add more complete multiseat support. If you are using Ubuntu, please try installing the version of LightDM in my PPA (<https://launchpad.net/~a7x/+archive/multiseat>):

    sudo apt-add-repository ppa:a7x/multiseat
    sudo apt-get update
    sudo apt-get upgrade

More complete instructions can be found by visiting the PPA page.