This thread really belongs in the CloneDVD section. But anyway…
You have not stated what settings choices you made in CloneDVD when you made the backup. If you copied the entire original disk via either compressing or splitting onto two disks, then unless you accidentally or purposely deselected the main movie soundtrack (2cnd page of CloneDVD’s film strip interface when using the “Copy DVD Titles” or “Clone DVD” methods) when you made the backup with CloneDVD, the main movie soundtrack is on the backup disks.
Use the “Audio” button on your remote control to cycle through the tracks till you find the right track. Or select the movies soundtrack from the DVD’s menu.
But, on many original movie DVD’s, the authoring is such that the soundtracks choice is matrixed through the menu structure, so if you chose to copy the movie without the menu, you must remake the backup, but this time check/click-“ON” the “Preserve Menu” feature in CloneDVD.