The ARP Ensemble Organ

There was some discussion of the ARP Ensemble Organ on AH.
From Ivan:
"I finally found the photo!? Took me a few hours of digging through back copies of Musical Merchandise review.? It is from the August 1974 issue and was shown at the June 1974 NAMM show: link [pictured]

So what David has is the same unit that was called the "Arp Ensemble."? Evidently it was sold with a Pro Soloist to make it a three-manual organ per the letter I got from a dealer ages ago: [link]

While searching for this info I also found a pic of the rare double-keyboard Mellotron: [link]"

Previously from Dave Hillel Wilson of the New England Synthesizer Museum had to say:
"It helps to remember that the ARP String Ensemble IV was really the Solina, manufactured by Eminent and rebadged by ARP. I bought a Pro Soloist a few years back from someone who told me it was the top keyboard on an organ. I played this organ and it sounded amazing, so I bought it for the Museum. It is called the Eminent 310, and is similar to the 310 U used by Jean-Michel Jarre."

images mirrored here

Update via Milo Johnson in the comments:
"That "double keyboard Mellotron" looks to be the Mellotron/Novatron Mark V prototype, and the year would be correct for it. There were 28 or 30 units made before the company finally folded. The Mellotron Mark I, Mark II, and SFX Consoles were all double-keyboard models as well, and there were an approximate total of 500 two-manual Mellotrons made in the early days. Fast forward to nowm when both Mellotron and Mellotronics are offering or developing new two-manual Mellotrons."