If you use DVD Shrink to copy a disc, and it does not need to be shrunk, it can ruin the data. I'm having to go over that with a newer videographer right now. DVD Shrink is not copying software, it's a transcoder that reads video data. You do not want to use a transcoder to simply copy a DVD.
Only use DVD Shink on commercial discs that are too big, and you're making yourself a copy from the original. DVD Shrink uses DVD Decrypter
or Nero to actually burn the data when it is done shrinking it.
You cannot "shrink" homemade discs without entirely destroying it's quality. Either use a DL disc, or fix your errors that made your SL project too large.
I use RecordNow Max to copy discs. I have a DVD-ROM to read the disc, and at the same time a DVD burner writes a new one. The drives are on different IDE cables (opposite channels). I copy at 4x or 8x.
I also use DVD Decrypter
to read an ISO in the burner, then insert a blank, and write that ISO. This is for harder to read source discs