I have not tried simply because I have only one of those receivers, but I don't see why not... One receiver as a streaming server via webif, and the other having the stream information defined as an IPTV/Streaming service.
It might be a bit tedious to setup and not so convenient to use - I am guessing that calling the stream from the "client" receiver would not make the "server" receiver tune to that channel, so would work only if that transponder is already being tuned in on the "server"box.