With apologies to boba, I have a similar setup, but turning the UHF remote into an IR remote doesn't help, at least not in my case. What I want to do is use a single remote to control both receivers independently the way you would use a single remote to control a VCR and a DVD player. If only the ALT button allowed you to enter a device code for a 2nd receiver, I would be happy, but it doesn't.
The solution I found is to use the setup feature that allows you to change the remote input for the receiver so that one receiver uses input 1 and the other uses input 2. You do this by holding down the SAT button until it flashes 3 times, then entering a number and pressing #. If you do it when the receiver's setup info screen is open, it changes the receiver's remote input. But - if that screen is not open, it allows you to change the remote to control whatever receiver is set to that number.
It's kind of tedious, but it's better than getting up from the couch to hunt down the other remote. Does anyone know of a better way?