Has the academy ever rescinded an Academy Award?

Answer 1

No. It has done exactly the opposite. Screenplays written by Dalton Trumbo won two Academy Awards during the 1950s while he was being blacklisted for Communist influences. A 1953 Oscar for "Roman Holiday" was presented to Ian McLellan Hunter, who had acted as a "front" for Trumbo. A 1956 Oscar went to "The Brave One," which had been written by Trumbo using the name Robert Rich. No one accepted the award until 1975, when the Academy formally presented it to Trumbo under his own name. In 1993, 17 years after Trumbo's death, the Academy gave him credit for writing "Roman Holiday."