The DUALITY wallpaper was inspired by an amazing fractal freeware called ContextFree - http://www.ozonehouse.com/ContextFree/ . After some tweaking I produced the fractal shown here (image size reduced).
The best thing in Context Free is that it can render one fractal many times with random settings and, as a result, slightly different results. So I put two fractals together...
... and again, and again, and finally I had some 15+ fractals overlaying each other, filling almost all space around them (which was my purpose).
Next, I prepared the background - a simply gradient, a bit distorted in the middle with brush tool.
I added the texture to the background, using the same technique that I use on many wallpapers. (see https://www.vladstudio.com/photoshoptutorial/?cant_sleep_making_of )
...Then I added my set of fractals and put it to the left edge of wallpaper....
... and then made a copy and put it to the right.
...One final touch was using black brush to fill the gaps. That's all!