FreeRADIUS and assigning Framed-IP-Address per user per site via users file?

Perhaps this is not possible without fancier configuration using virtual servers, but it seemed like the following should have worked:

alice NAS-IP-Address == 10.10.0.1, Service-Type == Framed-User Framed-IP-Address = 10.10.0.2, Fall-Through = Yes alice NAS-IP-Address == 10.20.0.1, Service-Type == Framed-User Framed-IP-Address = 10.20.0.2, Fall-Through = Yes 

(etc)

The idea being that depending on which NAS (router) they connected to, they would be assigned an IP from it's /16 subnet. My understanding (which appears to be wrong) was that by having the NAS-IP-Address matching in place, it would fail to match the first entry if the request was coming from the 10.20.0.1 NAS and then match the second. But instead it appears that the second (and third, etc) entry per user never even gets loaded upon startup. No matter what order they're in, only the first entry per username in the file appears to even be checked, much less used.

I was hoping to keep it simple but do I have to use multiple virtual servers, one per NAS, with separate user files etc? Or is there another relatively simple solution, or maybe I've just done something stupid with my config above that isn't behaving as I expected?