[Zope] basic FSSession question

I'm probably missing something really key here, but I'm having difficulty doing multiple sessions in FSSession. I have a session and then, say, take some form data and push it to the session. If I'm on a different machine (different cookie / different SessionUID), and I get different form data and write it, it then overwrites the other data, implying that it's the same SessionUID. I thought that calling <dtml-call FSSession> from a different machine, would then create a new session with the SessionUID stored on that machine. How, then, do I get multiple sessions? There seems to be a severe lack of documentation for FSSession. ~ Astrogeek