MP3 Encoding - Joint VS Full Stereo

I know the MPEG-1 Layer 3 lossy format has little respect on a pro audio forum/newsgroup, but I just need to sum up what I have researched. I'd like to know if I'm correct on one point.

First of all I understand what joint stereo does, and that there are several flavors of joint stereo - MS Stereo(middle-side) and so on.

As for full stereo, it seems to me that full stereo is simply two mono tracks, each at 1/2 the constant bitrate of a constant bitrate mp3. IOW: if you have a 320kb mp3, the left & right each are encoded at 160kbps. 256? That's two 128kb tracks.

Am I correct on that last paragraph?