I still haven’t found a stand that comfortably holds two arranger keyboards. The width of the instruments makes it difficult....
As of now I’m using an Ultimate Support Apex stand for the top keyboard and a regular x stand for the bottom keyboard. If I use both keyboards with the Apex stand, it’s difficult to see the screen and buttons of the bottom keyboard because the top keyboard gets in the way....
When I first started to use multi keyboards, most of us used our second keyboard to our left side (usually for bass), our main keyboard straight ahead, and a "color" keyboard to our right... In a "U" fashion, all at the same comfort level. Average polyphony then was 6 notes per keyboard.
We than started to use "A" frames, setting them up "our way". They were sturdy but a little slow to set up.. they did allow our three keyboards and a drum machine.
Today, in all honesty, we only need to use one keyboard. A top model arranger keyboard can cover all the bases. Plenty of polyphony, a single stand, on board mixing, mic input on board... How much easier can it get.. If you find/found the one keyboard that you really like , you have everything in an easy set up.. Many keyboards today can be a one keyboard set up.