Depends. You MUST have each of the 5 computers with a different computer name as within the WindowsImageBackup folder, the name of the next directory node is %computername% (in my case, JIM-GLH).
When you fire up Windows Recovery Environment, I believe (I can't test this as I only have 1 PC) it will show all system images found within all mounted drives (external included). It will list this "2nd" node on the right-hand side in the list of images Windows has found.
drive:\WindowsImageBackup\PC-1\Backup 2012-01-12 123456
drive:\WindowsImageBackup\MOM-PC\Backup 2012-01-16 135721
Win RE will list PC-1 and MOM-PC as possible images to restore from. YOU choose which to restore.