Not sure that I fully understand what the question is asking, but if you want to talk about the Duality of man, then it is a theory that all men have both good and evil inside them. Perhaps it works as a balance? Perhaps like a Chinese Yin and Yang? Good source is the scene from Full Metal Jacket where Joker explains his Peace sign button on his uniform together with the written words Killer on his helmet, and states perhaps it has something to do with the Duality of Man!

"Duality" is on Vol. 3: The Subliminal Verses.

the duality of paradox in your life is the square root of muffin

Planetary Duality was created on 2008-11-11.

The concept of duality means that every business transaction will have a dual effect on the accounting equation.