WITH upmarket hamburger restaurants the Hard Rock Cafe and Planet Hollywood set to do battle for custom when they open in Canton Road, Tsim Sha Tsui, we hear of a mammoth US$1.5 billion (HK$11.6 billion) legal battle being waged in the US between the rivaleateries. Restaurateur Mr Peter Morton, owner of chic Los Angeles hangout Morton's and all the Hard Rock Cafes in the western half of the US, is demanding the sum from Planet Hollywood's principal owner, Mr Robert Earl. Mr Earl, who numbers film stars Arnold Schwarzenegger, Sylvester Stallone and Bruce Willis as his chain's biggest investors, is accused of stealing trade secrets, creating a ''lower-quality knockoff'' of the Hard Rock and conspiring to invade the Hard Rock territories, a move that would not only take a bite out of the burger business but also eat into lucrative merchandise sales. Mr Earl apparently lured away a generous helping of Hard Rock employees to staff the flagship Planet Hollywood when it opened a block away from the New York Hard Rock. Long stretches of the Planet Hollywood employee manual seem to have been copied verbatim from the New York Hard Rock's manual, it is alleged. Recently, a Californian judge refused Planet Hollywood's plea to dismiss the case and the two sides are awaiting a date in court to fight it out. Hongkong residents, who have made imitation into a fine and honoured art, must be wondering what all the fuss is about.