If I have an HR23, an H21, and a D12, can I watch 3 different recorded programs simultaneously, one via the HR23, another one on the H21, and a different one still on the D12? I can see doing the DVR and another receiver at the same time, but I don't know about the third receiver. Or the combination of the H21 and the D12. Or can the DVR stream only one program at a time?