When multiple sessions per user is allowed we try to keep them on the same agent server in order to avoid problems.
The problems usually come from applications or desktops that incorrectly assume there can only be one session per user and system. The most common problems are related to shared homedirs.
It would be nice if this reasoning could be documented somewhere.
While we're at it, it would also be nice to warn the sysadmin of the potential problems of allowing multiple sessions per user.
The documentation looks good!