Not that I have access to any source code to verify this hypothesis, but there is likely an undisclosed command to do that. Unfortunately then someone could use the second drive to make copies of program material (aka video piracy), which would violently upset the legal copyright holders and content distributors. And the 1 TB capacity of the basic drive be a capacity issue.
Are recordings made in a format that can be read by Windows, Apple, or Linux Operating Systems? When I last had the portable hard drive connected to the Scientific Atlanta Cable Box, the files could not be read by an ordinary computer. Files were not .avi or .mp4 or anything I'm familiar with that can be read elsewhere. I would think Arris would do the same thing as Scientific Atlanta did several years ago, so that piracy would be virtually impossible without massive effort. Of course, i know that there are guys and gals out there who are capable of taking whatever file is on the Arris Hard Drive and converting it to something that could be read, but, i suppose, those folks are very few, and I doubt they would spend the time doing that as the programs I would record are easily found on Pirate sites already. I cannot see any actual advantage to record in order to pirate. It's a bogus issue.