Barry Fitzgerald - Best Supporting Actor and Best Actor (1945)
Every once in a while an actor will receive two acting nods in the same year - Al Pacino, Emma Thompson and even Jamie Foxx have held that honour among precious few others.
However, Fitzgerald is the only actor to receive two separate Oscar nominations for the same film! Due to a lack of planning and no rules in place to say otherwise, he was promoted for a nomination for his single role in 'Going My Way' in either category - instead he received both.
To top it off, he managed to win the Supporting Actor award, losing the leading honour to his co-star Bing Crosby. In the end, the film received seven Oscars including Best Picture fuelling further controversy as Billy Wilder's 'Double Indemnity' was the shoe in. Since the debacle, the Academy's ruled have been amended.