Get audio file from dup dvds?

Hi all, i been searching for help long enough and now desperate…please help, I need to rip audio file ac3 from dup dvds which made from dvdx copy express or dvdx copy(both give out the same quality). I tried smart ripper and dvd decrypter to rip those dvds but they could not detect any audio files ! any sugestions ? any other alternative softwares to use ? Oh one more interesting thing: i even use power dvd to play vobs file orignal from the dup dvd, it does not have any sound ! but if play normal like insert the disk and click play, it works just fine ! dvdx copy is a genius to against dup dvd allow you to duplicate one not second time.