Open the files on the disk with DVDShrink. Got to ReAuthor in Shrink and see if there are two titles in the dvd compilation. If so, you can select just one of the titles at a time to save to a separate dvd.
If there are not two titles, do the same steps, but this time use the Set Start/End Frames tool within DVDShrink to choose the exact areas of the dvd that you want to save to the new dvd.
By the way, you shouldn’t need to use any compression when saving these sections, so don’t be put off by the name of the tool.
DVDShrink can be found at www.mrbass.org among other places. This guide should give you the basics on using the Set Start/End Frame tool when in ReAuthor mode using DVDShrink: http://club.cdfreaks.com/f72/guide-dvd-shrink-part-4-advanced-re-authoring-77120/