That's a Kaman HH-43.. German dude named Flettner, that got spirited to the US under the same banner as Werner von Braun and others, came up with that. The reason counter-rotating designs of all kinda fell to the side is that you lose a lot of efficiency when your two rotors are busily sucking down each other's rotorwash. The two side-by-side idea is arguably less mechanically complex than the way the Russians do it But even the Russians, who did fundamentally ludicrous things with helicopters Got it down to one when they got serious about it.
You are truly a fount of knowledge, my friend. That's the one. I noticed a couple of your image links didn't embed - and those links start with "https://" - I thought that #bugski was fixed? mk ?
Aaaand now, they seem to have repaired themselves. Edited, I assume.