Audio for clips brought into timeline

I am a newbie to CS5 and have an audio question.

Whenever I shoot footage in the field, I record the subject using a lav on Ch1 and the cam mike is Ch2. When I import clips into PP and bring into timeline, only one stereo audio track appears which is the lav. If I am recording 2 channels, why is it that a second track of audio does not appear? Is it because both tracks are mixed together? Because when I play the clip in the timeline, I hear the subject voice out of only the left speaker, Subsequenty, I shot fooatge using two subjects using Lav1 on Ch1 and Lav2 on Ch2. In the timeline, the one audio track appears and I hear the Ch1 subject well, but the subject 2 voice is distant. Why doesn't Ch2 track appear?

I am trying to understand what the best option with audio? For the first example, I used Fill Left so the subject would be heard out of both speakers evenly. How do I handle the second example?

Thanks, Steve