I just got of the phone with some guy at a dub house... I'm getting a mini dv transfered to Beta for Broadcast. He told me that my audio was split and that I should mix them down.
What's the proper way to do this? I'm using Premiere Pro

Sounds like they're telling you some of your tracks are going to either the left or right channels in a checkerboard fashion instead of being mixed into both L & R channels equally. Stereo tracks can remain stereo with both channels distinct but mono tracks like dialog, narration/VO, or SFX should be panned equally between both channels. It's very disconcerting to the viewer for the narration or a character's dialog to jump from one side of the screen to the other as you cut from shot to shot. The pan controls on each audio track in Premiere's audio mixer govern its placement in the two output channels of the final mix. When you listen to your mixdown be on the lookout for any phase issues that might sneak in to bite you - a stereo mix that sounds fine when played back in stereo can fall apart and sound awful when played back in mono and a substantial portion of your audience is going to hear it in mono when you go to broadcast. Even if they're listening in stereo, if the two channels are out of phase it can sound really bad.