Control of 1 Genie C-41 (HR44) with 2 RC71 Remotes

I need to know how to set up two separate RC71 remote controls to control one DirecTV Genie C-41 (or HR44.) The primary remote is set for RF, and I would like the secondary remote to operate with RF also, if possible, but if both remotes need to be IR, that would be OK. I saw on a DBSTalk Thread that this can be done with the "Copy Settings" function, but I cannot get that to work.