Actor Michael Keaton’s real name is Michael Douglas, and he now plans to start going by that name, many decades into his professional acting career. But the name change won’t start with his next film, Beetlejuice Beetlejuice, which releases on September 6.Keaton told People that he chose the name “Michael Keaton” by thumbing through a phone book one day a long time ago. He couldn’t use his birth name, Michael Douglas, because the Screen Actors Guild forbids members from using the same name. Michael Douglas, of course, is famous for a great variety of roles and performances, including Oscar wins for Wall Street and as a producer on One Flew Over the Cuckoo’s Nest.”I was looking through–I can’t remember if it was a phone book,” he said. “I must’ve gone, ‘I don’t know, let me think …