Some background: In the spring of 1966, Alfa Romeo held a contest to come up with a more memorable name for their then just-introduced 1600 Spider. Entry forms were available at dealerships around the world to solicit suggestions. The lucky winner was promised a brand new spider. Over 140,000 entries poured in; among the suggestions said to have been proffered were "Pizza", "Hitler", and "Sputnik." Variations on "Pini" and "Pininfarina" were most popular, perhaps because the noted coachbuilder and designer had just passed away that April. (In fact, it is said the contest subject was the last car Battista "Pinin" Farina had an active hand in designing.)

As it turned out, the eventual winning name "Duetto" was proposed by many contestants, and so a drawing was held to chose a winner from among them. Thus, on June 17th, 1966, the keys to a brand new Alfa Romeo Duetto were handed over to Guidobaldo Trionfi of Brescia. Unfortunately, the large confectionary firm Pavesi objected, claiming that it infringed on their biscuit and filling concoction of the same name. It seems therefore that Alfa took the first opportunity to quietly drop the name with the introduction of the 1750 Spider Veloce in January 1968. Very few official Alfa documents refer to the car by the name "Duetto." For instance publications such as the owners instruction book and factory parts catalog were not revised in subsequent printings to reflect the new moniker. At any rate, Italians have always favored the nickname "Osso di Seppia" (cuttlefish bone) for the roundtailed spiders; "Duetto" is used by many Italians generically to describe all the spiders built between 1966 and 1994. In the US it is generally considered correct to refer to the original 1600 version only as a "Duetto," even though the later 1750 roundtails are virtually identical visually.

Source: Alfa Romeo Duetto Spider by Giancenzo Madaro, Giorgio Nada Editore, Milano, 1990