The answer is yes and no. If you are recording your audio in an outside program, or say, to a pair of Zoom H1 field recorders, then yes you can import both audio files onto separate tracks in camtasia.
Camtasia, however, does not currently have a feature that would let you bring in multiple mics, and then break them out into separate channels. I tested this by creating a 4 channel device and choosing to record it in Camtasia. Camtaisa displays a single audio waveform and I didn't see any option to 'split, separate, isolate, etc' the audio portion into it's respective channels.