None of this changes the fact that Bill Parker designed the character as two different people and Otto Binder to a lesser extent both wrote them as seperate people:
Here's some additional things that Beck added as far as how limited his input was on the character in the same interview Orchid is referring too:
No. At Fawcett, Captain Marvel was produced by writers and artists working separately. The scripts were prepared by the editorial department, the drawings by the art department. The writers, who worked under the supervision of a managing editor, had nothing to say about the art, and the artists, who worked under the supervision of an art director, had nothing to say about the stories they were given to illustrate. In the 13 years I spent drawing Captain Marvel, I wrote only one story, about Billy’s trip to a Mayan temple, which had to be submitted in typed form and edited and approved before I was allowed to illustrate it. There was never any direct cooperation between the writers and the artists at Fawcett, but there did develop an interplay of ideas between the two departments that kept Captain Marvel changing and developing instead of getting bogged down and repeating himself tiresomely after the first few issues, as so many other comic characters did. Ralph Daigh, the editorial director at Fawcett, has said that I had complete license to change and alter scripts to suit myself. I don’t remember his saying this to me back in the days when I was drawing Captain Marvel.
Which is why Alan Moore, Stan Lee and other creators designed their knockoffs the same way. He was always originally two different people know matter how you want to split hairs.