When it comes to corporate rivalries, few can equal the scale of the tiff between Japanese electronics giants Sony and Matsushita. In the 1970s, Sony invented the Betamax VCR. Matsushita threw its weight behind VHS. Score one for Matsushita. Over a decade later, Sony bought CBS Records and Columbia Pictures. Not shy about keeping up with the Moritas, Matsushita bought MCA, thereby picking up a record company and a movie studio. Pretty impressive, but was either company satisfied? Last year Sony started hawking its digital audiotape (DAT) decks a technology that allows supposedly perfect recordings of audio CDs to U.S. customers. Had Sony finally shaken loose of its rival? No such luck. Matsushita is reportedly helping to develop digital compact cassettes (DCC), a noncompatible format due out in 1992. Culture buffs, take note: Maybe it's time to consider the history of American entertainment as one all-dominating struggle for supremacy between foreign superpowers. To wit, after Sony gained rights to The Three Stooges Meet Hercules, Matsushita countered by acquiring Abbott and Costello Meet Frankenstein.