yes they did and still do...here is an offy-equipped chevy 230 in my 65 van...2x1 intake adapted to 2 dueces.
i have seen a few 2x2's and even a 2x4 /6 intake on ebay, i think clifford still makes multi-carb manifolds for the slant, not sure tho.
multi carbs have huge wow factor but i would have went with the single 4bbl with a 390 holley on my chevy, except it wouldn't fit in the doghouse. so i chose to go with the 2 doubles instead. tuning it was a nightmare especially since i was new to that sort of thing when i built it. but once it was set up right, it was really nice and got just as good gas mileage as the original 1bbl carb with a LOT better throttle response and power.
-tim