good way to do dual audio into an mp4 / mpeg4? (megui vs yamb / mp4box)

[plonk420]

i found that yamb / mp4box can do 2 (possibly more?) audio streams in an MP4, whereas megui's interface only has room for one, but my friend found that you can take said a/v mux, run it thru the muxer again, and you will get two audio tracks. is this a legit method resulting in a valid mpeg-4 stream?

[Lighto]

It can be easily done with MeGUI.
http://i.imgur.com/p2fJn.png

[plonk420]

oh, TIL!

thanks!