Multiple angles in converted video

Hi everyone,

this is my first post here so please bear with me.

I recently downloaded a workout dvd rip. It came in vob, bup, and ifo files and everything appears to be in order. The vob's play fine in VLC.

I found out that original dvd featured both front and back angles for viewer convenience. The problem is when I convert the files to mp4 to watch on my nook, something weird happens. I see a mix of front and back angles while the audio plays in a glitchy loop. like "hello guys, today..." *glitch* "guys today we're going" *glitch* "we're going to be" etc.

this has happened when i used both handbrake and leawo's video converter.

so clearly the two angles are getting all mixed together. what i want to know is if there's anything i can use to take appart the dvd's separate elements and, like, extract just the front angle?

Thanks guys.