This happening on all copies, or just a specific title? I've backed up a bunch of my originals and have never seen vertical lines on a copy.
It could be an issue of your player not liking your media. If you are using -r, try some +r, or vice versa.
Or, it could be bad media. Try something made in Japan.
Or, it could be that you are burning too fast, go into your burning option (F9) and set your burn speed to 4X.