You need to change one of the Hr20's to the alternate IR codeset, 00003. When changing one receiver cover the other.

First program code 00003 to either av1 or av2 on the oem remote. slide back to dtv symbol device and enter the menu of the receiver;

1. menu> settings> setup> remote> receiver mode>

2. you will see either DIRECTV or AV1/AV2, click whichever to reveal both

3. press AV1/AV2, the remote shouldn't work any longer, slide to av1 or av2 whichever has code 00003

4. press done.

I'm sure the mx950 must have this alternate codeset in its database??