Nope doesn't happen to our DISH DVRs. We take both of our 722 DVRs and put them in the motor home that has a DISH equipped Wineguard Trav'ler. All the programs that we have recorded at home stay on the DVR and we continue to watch them at our leisure in the motor home.
When we get to Oregon, I delete all the set recordings for the local channels at home (LA stations) and then go through the program listing and then set up the recording of the same programs but from the Portland local channels. I keep all the non-local channels that I have set up for recording as the channels don't change.
Works for us.
Ron