OK... have you all beat....
in the late 80's... I actually played and traveled with 9 keyboards at one time.
These consisted of 3 Ultimate Support 3-tier Apache style stands, each holding 3 keybards, arranged in a u-shape. I can't remember all the keyboards becuase they have been given away, were borrowed, etc. Some were ROland JX-3P, Yamaha YP-40 (The first ever Clavinova), Korg DSS-1 sampling synth, KOrg SG-1D sampling grand, Korg Ploy-800, a few mono synths, a Crumar Traveler Organ
Some of them I used one sound on one song and 2 I never even plugged in... they were for looks...
I was 19 or so and they just looked cool. I even went through a "red rocker" phase and painted all three stands fire engine red, painted some of the keyboards and the mixer the same red and even bought a matching red pants and top to match (including a single red fingerless glove).
Anyway... I'm down to 2 for my gig these days...
Yamaha DGX-500 and Korg PA1x-Pro
Have 6 other keyboards around my office, studio and home studio.
Jeff