Freeradius not unescaping \ and "

I have the following setup: CoovaChilli accepts user login requests and sends radius packets to freeradius freeradius then proxies the requests (based on realm) onto a second freeradius server. If I attempt a login with username "A\" The first freeradius server recieves packets with UserName atribute = "A\\" and sends a packet to the sencond radius server with username attribute = "A\\\\" (as reported by wireshark) So it looks like freeradius is not correctly unescaping the username attribute. (Or incorrectly re-escaping) before the proxy. How is freeradius expected to behave when escaping backslash and quote characters before proxying? And is it possible to alter this behavior though configuration? Thanks, Murray