Is it possible to record simultaneously from two stereo mics? (One attached to the hotshoe and one attached to the mini jack.)

Canon's specs state:

Audio
DV: 16 bit (2ch) 48 kHz
12 bit (4ch) 32 kHz
4ch synchronous recording not possible

HDV: MPEG1 Audio Layer II (2 ch)
(4-channel playback of tapes containing 4-channel recordings possible)

This would seems to indicate no, but I'm not sure if I'm reading it correctly.

I would never use the default 12 bit because of the inferior audio quality.
HV20 will only record 1 track as far as I know. The 12 bit mode allows you to add an additional track later, but it's better to use 16 bit and use software to achieve the same.

You could mix 2 signals to the mini jack. That's the only option I see.

Luc is right about 16bit mode for audio.

The HV20 definitely records two channels in stereo mode. The question is how to get different audio to the two different channels since there's only one mini-jack.
I'm assuming I can do this with my Beachtek DXA-2s - just haven't had a chance to test it yet. Will try it before I leave for vaca next week.

Thanks guys for your help ;). So essentially, two mono inputs (2 channels) should be possible. But two stereo inputs (4 channels) is not. Is that correct?

Thanks again.