You're referring to the RRM Profile Threshold for Traps setting, right? This does nothing to restrict the number of clients allowed on an access point. This number simply determines when an access point sends an SNMP alert to the controller. By default, once the 13th client hits an access point, it alerts the controller.
Again, this does not affect the functionality of the access point or controller, or even the RRM algorithms. As such, nothing happens to the 13th client. You can read about it in this document:
Transferring Crash file from standby: Login to the Active WLC in HA.
From CLI: (Cisco Controller) >transfer upload datatype crash (Cisco
Controller) >transfer upload filename (Cisco
Controller) >transfer upload mode tftp (Cisco Controller) >transfer
This is the start of a display filter cross reference between Wireshark
and OmniPeek. The 1st installment is a table of advanced filters. More
filters will be added as time allows. It is a living doc, so check back
for changes every so often Please feel f...