Configuration problem with Hotspot

I’m having trouble with HotSpot and Framed-IP-Address, trying to avoid tying up 2 IPs for a single client and banging my head against the wall. HS is running on a MT router, doing MAC authentication to a RADIUS server. Some of my customers have reserved addresses (Static DHCP) within my current configuration that RADIUS sends with Framed-IP-Address, but most are just plain DHCP public IPs. If I have the HS pool set to the public IP pool and RADIUS doesn’t send a Framed-IP-Address, clients work. If the HS pool is set to the public IP pool and RADIUS does send a Framed-IP-Address, the client winds up tying up 2 addresses (the original DHCP address PLUS the Framed-IP-Address, as HS seems to be doing IP translation). If the DHCP pool is set to a private IP pool, the HS Address Pool is set to a public IP pool and RADIUS doesn’t send a Framed-IP-Addresss, clients don’t work (HS shows translating the private IP to the same private IP). In the same configuration where RADIUS does send Framed-IP-Address, it works and only ties up the one IP. In the same configuration where RADIUS sends Framed-Pool (but not Framed-IP-Address), it works and translates them to a single public IP. In the same configuration where RADIUS sends both Framed-Pool and Framed-IP-Address, HS is translating to a dynamic (pool) IP, not the Framed-IP-Address.

Any ideas where I should be hunting?