Were two-tones that rare? And was the second color restricted to black or white? I've seen one at local car shows that is definitely a two tone: silver over metallic gray.
The two-tone paint job pretty much went away by 1966 at GM, due mostly to body styling thatno longer offered a logical dividing line or point for color separation, which would have meant either an awkward-looking paint scheme, or serious delays in the paint & trim department of any GM Assembly Division plant, due to the necessity of being very precise in masking for the second color.
Even the vinyl tops of the era made for some interesting work for sure, particularly with Chevelle/Tempest/Cutlass/Skylark bodies having adopted the "flying buttress" roof design with the back window tunneled in as it was. As such though, vinyl tops tended to be either black, or white (at least those were the most common colors), with both colors being available with nearly every body color, I believe.
Two-tone, or even multi-colored paint jobs go all the way back to the earliest cars though, and became very popular in the 1920's with the introduction of spray painted lacquer finishes that began in 1924 at Oldsmobile (DuPont Duco Lacquer, provided by DuPont, at the time the principal stockholder in GM). Of course, most cars prior to about 1930 had black fenders, running boards & splash aprons, but that was pretty much a carryover from horse-drawn carriage days. Complimenting colors were used to highlight sculptured window reveals, even the raised moldings on those old upright, squarish body shells, along with pinstriping which was the primary body trim before chrome spears.
In the bottom of the Great Depression, multicolor car bodies went out of fashion, as those who could afford to buy a new car generally declined to "show off" anything that smacked of affluence in the face of breadlines in many cities. By about 1938 or so though, two-tones came back, at first limited to those fat fenders being painted a different, often contrasting color to that used on the body--usually black, or a dark color of some sort.
After WW-II, a few makes, notably Buick, Pontiac and Packard, became available with a complimenting color emphasizing the body character lines of hoods, roofs and rear decks. With the wholesale introduction of new, postwar body styling by 1949, most carmakers began offering two toning, but pretty much limited to the roof, where the second color could easily be separated from the lower body color either by the sharp crease at the bottom of the roof where it joined the lower body, or by the use of chrome trim to cover the masked separation.
With the popularity of "sun belt" oriented images in advertising, by about 1954 or thereabouts, the white roof came into serious vogue, although dark roof colors were still available. But with white, ostensibly that made the interior of the car cooler in the hot summer sun, in those days before the almost universal adoption of air-conditioning. Very quickly, a white top became almost mandatory, if for no other reason than to "keep up with the neighbors", darker optional roof colors beginning to disappear from the paint charts at the dealer's showroom.
But everything "has its day" of course, and by the early 1960's, two-tone cars, mostly with white tops, began to be seen as old-fashioned, "last year's" styling, the emphasis being on "new" every year.
Vinyl tops, on the other hand, have their roots way back in the horse-drawn carriage era, when closed carriages had black leather roofs to seal out rain. With early cars having bodies built in the carriage tradition (coachbuilt bodies), the same issue with roofs on closed cars remained, how to seal a multi-paneled construction body shell against inclement weather, so at first leather, then various treated or coated fabrics began to be used, with rubberized or plasticized canvas duck being used until the development of one-piece stamped steel roofs (GM called them "turret tops" which swept across the industry by 1936-37. Leather-grained black vinyl continued to be offered by Packard on their senior cars, Cadillac on Series 75 and Series 90 sedan limousines, even Buick on their Series 70 sedan limo. Chrysler installed a few on late-30's Imperial 7-passenger sedans as well, but by WW-II vinyl tops were gone.
Fast forward to 1950: Ford Motor Company, having been blind-sided by the unveiling of Buick's Roadmaster Riviera hardtop, followed very quickly by the Cadillac Coupe de Ville, Oldsmobile Holiday, Pontiac Catalina and Chevrolet Bel Air Hardtops, rushed to introduce up-trimmed 2dr sedans; Ford Crestliner, Mercury Capri, and the Lincoln Lido, all of which sported vinyl top covering, in black, as well as dark green, dark blue, and even maroon; as midyear 1950 introductions. Those carried over into 1951, but were overshadowed by the addition of the Ford Crestline Victoria hardtop, and the vinyl topped 2drs disappeared at the end of the '51 model year. Kaiser tried using vinyl tops on their 1955 Dragon, but to little avail, that car sold very poorly, and Kaiser exited the passenger car business by the end of that year entirely to concentrate on Jeep. The next fling with vinyl top treatment came at Cadillac, introduced on the all-new 1959 Eldorado Seville, the majority of those being produced with white vinyl on the roof (now you know why Monogram chose to do their excellent kit of the car with a vinyl roof!), and continued that into 1960. With the coming of the "formal roof" hardtops at GM in 1962 (actually, those were styled to imitate the shape of a raised convertible top!), they played around with offering vinyl covering on those, but I never saw very many of them. Rather, it was Ford who made vinyl tops a "have to have" with the introduction of their "quieter than a Rolls Royce" LTD sedans in 1965, which probably inspired Chevrolet to specify black vinyl roof treatment on the '65 Chevelle Z-16; the treatment spreading across the Ford line, very popular on the Mustang Coupe. Everyone followed suit by 1966, and the rest, as they say, is history.