NAS re-uses the same port and ID

Hi all! I've found, that our NAS-server sometimes (when it restarts and there are many auth. packets comes to the radius-server) re-uses port and ID in a < 1 second period. (information from tcpdump) That causes " conflicting packet from client". I think, that the NAS works wrong (it must wait a little bit more, then 1 sec. to re-use the port+ID), that's why I wont to find some documentation about it for a bug-report. Thanks a lot.