OK - I think I've found perhaps the origin of Dual Binaural Beats.

This is something I've been referring to as more than two channels of audio or similar. The bad technology is due to the fact that I use software for creating and mixing audio and so I used like terminology.

Photosonix is the creator of Nova Pro 100 Light and Sound device which allows for the user of dual binaural beats and dual monaural beats.

I have included a bit of a description below for anyone that's interested:

dbb (dual binaural beats) dual binaural beats were first experimented
with by Robert Monroe. He used them to induce “out-of-body” experiences.
His main formula was to use combine a beta frequency to keep you
alert, with a theta wave, to induce a dream state. The idea was to induce a
state of “mind awake, body asleep.”

When it comes to dual binaural beats no one is exactly sure what state of
mind the combination of two brainwave states will actually produce.
Different people will have very different experiences with the same
combination. For that reason, Robert Monroe used a whole lot of different
combinations in his signature series, “The Gateway Experience”, so that
just about anyone would find a combination that work well for them.
You can do the same. If you experiment with dual binaural beats, you will
see what combinations work well for you.
Also - here is a description of dual monaural beats.

dSb (dual monaural binaural beats) This tone allows you to create a
different brainwave frequency in each ear. Sound heard in the left ear is
processed by the right side of the brain, and sound heard in the right ear
stimulates the left side of the brain.

The left side of the brain is responsible for analytical thinking, math, and
logic; whereas the right side deals with abstraction, art, and creativity.
Using dual monaural beats, you can adjust the activity in each side of the
brain, or hemisphere, to either be more logical, or creative.

If you want to be more analytical, then you would adjust the beat frequencies
in the right ear so that they are faster than the frequency in the left ear.
To be more creative, you then want the frequency in the left ear to be
faster than the right ear. Faster beat frequencies would be in the alpha and
beta ranges, above 8 Hertz. Slower frequencies would be in the theta and
delta brainwave states, below 7 Hertz.

The use of dual monaural beats is quite new to the field of light and sound,
therefore, there is not a lot of documentation on exactly how it’s effects
really work. There also is not an exact science as to what each side of the
brain really does. While the right brain pertains to creativity, such as
processing music, many trained musicians use the left brain when playing
music. This highlights the fact that the brain is much more complex than
any “model” can define, and that you will need to experiment in order to
find out what actually works for you.
This looks like trail-blazing and doesn't appear to have the same grounding as the regular binaural beat theories.

It does seem that Robert Munroe does have something to say about dual binaural beats, but I'm having difficulty actually finding what papers were produced on the topic. I've had a look at The Gateway Experience website and the site on Hemi-Sync, but am not finding much at this stage on dual binaural beats - plenty on binaural beats themselves though.

It's also disconcerting to always find these papers freely published only on sites trying to sell you something, but that's another story.

Regards
Caleb