When I breakout a stereo clip to mono in Premiere Pro 5 what must I do to be able to place the 2 files on separate audio tracks - they both want to be on the same track at the moment.

Sounds like you are trying to place your new mono clip into a stereo track. You have to create a mono audio track. For more info, check these links:

Adobe Premiere Pro CS5 & CS5.5 * Work with tracks (http://help.adobe.com/en_US/premierepro/cs/using/WS8B5B3781-B58A-4aa8-BFC8-C55A6A29B5F4a.html)
Adobe Premiere Pro CS5 & CS5.5 * Overview of audio and the Audio Mixer (http://help.adobe.com/en_US/premierepro/cs/using/WS1c9bc5c2e465a58a91cf0b1038518aef7-7f58a.html#WS1c9bc5c2e465a58a91cf0b1038518aef7-7f56a)

Much simpler than that. Highlight the combined video/stereo audio clip in the project box, NOT the timeline. Then go to clip, down to audio options, then breakout to mono. Two new mono tracks will appear, and you can then put them on the timeline, and have access to the pan control to place them wherever you like in the stereo field. This works on CS4 and 5.

Paul

That's a really good technique for keeping all your audio on the proper tracks. Thanks Paul!