To check Simultaneous against 2 NASes

Hello, 2 identical servers (CentOS release 5 (Final) running FreeRADIUS Version 1.1.3 with MySQL (Ver 14.12 Distrib 5.0.22) MySQL on both - master and slave to each other 2 NASes authenticate and do accounting to either FreeRadius server. checkrad is used to handle Simultaneous Logins How can I set up to check Simultaneous Logins against of both NASes? For example, a user goes through NAS1, freeradius server checks only that NAS1 if the user is connected. How can I make it to check against of both NASes? Thank you for your help in advance. Irina