passive management server a notification requesting that the duplicative managed device be deleted from the passive management server 39 s management list step s 7 the active management server then continues to manage the managed devices as before step s 9 in the specific example shown in fig1 where the first management server 8 is the active management server and the second management server 9 is the passive management server for example the first management server 8 asks the second management server 9 to delete the third and fourth image forming apparatuses 5 and 6 and the scanner 7 which comprise duplicative managed devices from the second management server 9 39 s management list and continues to manage the first through fourth image forming apparatuses 3 6 and the scanner 7 when the passive management server deletes the duplicative managed devices from its management list duplicative managed devices no longer exist between the active management server and the passive management server in other words all of the managed devices are managed by either the active management server or the passive management server and none is managed by both management servers in a duplicative fashion if on the other hand the duplicative managed device does not reside on the local area network to which the active management server is connected no in step s 5 the active management server determines whether the number.