I don’t think the failed burns have anything to do with the fact that you are burning a backup DVD. Your backups already have the copy protection removed. At that point, it’s just data. Are you burning your DVDs on-the-fly? You should never do that (burning a DVD directly from a DVD in your DVD drive). Your drives transfer data too slowly and pauses which ruins burns. Because your backups have no copy protection, you should just drag the VIDEO_TS folder over to your hard drive. Defrag your hard drive, then burn. If you have problems copying the backup DVD to your hard drive, it’s only because the DVD disc is either scratched or it’s just bad media and is unreadable (cyclic redundancy error). That will stop any DVD burn in its tracks. You can recover most of it by using DVD Decrypter and just checking off the boxes to tell it to skip the errors (0 retries).
P.S. If you’re burning from your hard drive and get errors, your DVD burner might be dying (the laser is dirty or something else). I’ve been through 6 DVD burners, and the first sign of it dying is failed burns in the middle of burning. You can probably squeeze a few more burns out by burning at a slower speed, but your PI/PO error checks might still show bad results. Think of replacing your burner and using your old one simply to play or rip DVDs.