actually a single SD remote will work. You need to program the 2nd box to another address and manually use one of the remote devices (eg aux). To do this you need to follow the instructions to set up your remote to work with a TV or DVD, just use the code 0001 or 0002 or 0003 up to 7(?) I may not have the correct of leading zeros, but I have done it.
You will need to make sure one of the receivers is off so you know which one is being changed.
1 - turn off a receiver, leave one on.
2 - go through the process of switching receiver address to 0002
3 - program your DVD button to 0002
4 - reprogram you SAT button back to 0000 if it was changed
receiver 1 goes on SAT button
receiver 2 goes on DVD button
I'm just going from memory, so I may not 100% spot on but this is basic idea.
Just the person I want to talk to.

I've been trying to do this for years, as we have all our receivers in one room. We had a 505 and a 530, now a 505, 530 and a 630. In years past, we were able to do what you're suggesting here with that "older" remote, I don't recall the model. It's the universal remote (non-IR) that came with SD receivers and still worked under that method of programming the remote code where you did the whole thing directly from that "Change Remote Address" screen. It has orange buttons at the top as opposed to red.
But the IRC550 and the RF600 work under a different methodology for programming devices. I've tried what you suggested to program one of our other receivers onto one of the other buttons, whether it be DVD, AUX, whatever, but it somehow *knows* when you put in the code 000 to 007 or whatever for a satellite receiver that it's for a satellite receiver -- and yes, I even tried it with four digits, like 0000 and it made no difference. It just changes the remote address on the SAT button. I've tried everything I could possibly think of, but have been unable to get it to comply.
I tried it again today after reading what you wrote. I even put on our DVD player, covered up the front of all the receivers, removed the antennae for the 530 and the 630. I attempted to put the AUX from the IRC550 remote on code 006, which is the code for our 630. I tried it with the DVD button too. When I finished, what it did was change the SAT code to 006, meaning it worked now with the 630, but the 530 didn't work.
I also tried it with the AUX button from the new RF600 remote, but it's even less flexible. Believe me when I tell you that I'm following the instructions correctly. I've set extra TVs, numerous things. But *specifically* to get either the IRC550 or RF600 remote to work with more than one satellite has been nothing but a dream for me.
Using the older remote, obviously, isn't really an option for anything other than the 505, as it's missing many of the necessary buttons for the 530 and/or 630 as it wasn't designed for a receiver of this type.
So, if you actually found a way of doing this with either the IRC550 or RF600 remotes, I would totally appreciate it if you could write here with the instructions of *exactly* what you did to accomplish this. It would be greatly appreciated.
The Hans
Sitting with a remote for the 505, 530 and 630, not to mention one for the TV...