A clearly confused Beatty hesitated after opening the envelope, so he handed it to Dunaway who immediately announced La La Land.
It was a tense moment as Warren Beatty and Faye Dunaway took to the stage to bestow the honour on the winning film after last year's epic blunder. "I wasn't trying to be amusing", Beatty clarified on stage at the time, after host Jimmy Kimmel had joked "Warren, what did you do?"
And all three accountants were scheduled to attend rehearsals and practice any mix-ups if one slips through, the firm said.
So this year the Academy took some not-so-minor and obviously very important steps to make sure such a fiasco didn't happen again.
In a moment of pure chaos, Jordan Horowitz, a producer of "La La Land", later set the story straight: "Moonlight" was the true victor.
He said to the Hollywood Reporter: "It's bittersweet because when that switch happened, I didn't enjoy it". I'm afraid they read the wrong thing. So, there was nearly a stigma that I felt.
Picking up the evening's biggest prize, Best Picture, the director dedicated the honour to up-and-coming movie makers.
As she did with every other presenter, Bourdon turned to Beatty and asked: 'This is the best picture envelope, could you please confirm that?'
The drama, starring Trevante Rhodes, Ashton Sanders and Alex Hibbert, won three Oscars from eight nominations previous year.