How to play multiple tracks of audio at the same time

For some videos I create I use multiple audio tracks. When I want to play the video with the player, I hear nothing or 1 track at a time. Is there a way to hear all the tracks at the same time?

It supports at most two audio tracks. One from the video files, plus a dub.
Menu > File > Open File
(if you give dub same base name as the video file, then it gets loaded automatically)

You need to disable the internal audio switcher
Options > Internal Filters