What are you using to play the files back?
An .ogm is a container for the audio and video files, it should have the soundtracks as seperate languages, you can normally select which one to listen to as you would with a DVD.
So it might be that your playback software can't handle ogm files,
I think I used BS Player last time I played an .ogm back, it allows you to select which soundtrack to play quite easily.
If you need to export them seperately for authoring a DVD, or just to delete one of them, you can do it with virtual dub mod (free from: here), there's a tutorial here:
If they are actually encoded together then like Mr Mills says, it would be a nightmare to filter one out.
Panasonic SD9, Panasonic NVGS-75, Canon MV600i