Failed to add duplicate client problem

We have a vpn gateway with different URLs for different user groups. For each URL a specific radius server has to be defined. Up to now those different radius servers have been installed on different machines. When trying to consolidate those servers within different virtual servers on one single machine freeradius refuses to start with the "Failed to add duplicate client xx to clients list. Maybe there's a duplicate? " message. Yes, there is a duplicate and it is on purpose. Is there a way to cirumvent this? Mit freundlichen Grüßen Norbert Wegener