Store message "Multiple logins" in MySQL.

Hi All! I need to register in a database when occurs simultaneous use. Currently I stored by postauth_query through the variable '% (reply: Packet-Type)', but the message is generic, ranging from Access-Reject or Access-Accept. When a connection occurs simultaneously, The freeradius stores the message "Access-Reject" The problem is that this message "Access-Reject" is the same for when an error occurs the user or password invalid. Tell me about that you can do this by setting the Freeradius conf, without changing the source code?