Anne Hathaway "threw a fit" when she discovered Amanda Seyfriend's Oscars gown was similar to her own.
The 30-year-old actress originally planned to wear a Valentino dress to the Academy Awards but after Amanda, 27, showed her Les Miserables co-star a picture of her own dress, Anne reportedly flipped out.
A source told Us Weekly: "Anne was like 'WTF?!' She started throwing a fit! She never told Amanda she had to change the dress. Amanda didn't want to deal with it and left.
"I kind of can't understand why Anne didn't wear the Valentino gown, anyway. She was the one winning the award, not Amanda. Who cares?"
Best Actress winner Anne eventually chose a Prada gown but not before she made her team wait hours while she decided.
A second source said: "Anne made the fashion, make up and hair teams wait at her home for hours as she decided what to do about the dress debacle. She asked for silence so she could rehearse her singing for the Les Mis tribute at the Oscars. It was a painfully long experience."
Anne surprised onlookers when she arrived in the pale pink Prada gown at the Oscars just hours after Valentino released a statement saying they had dressed her for the high profile event.
She issued an apology, saying: "Though I love the dress I did wear, it was a difficult last minute decision as I had so looked forward to wearing Valentino because of the deep and meaningful relationship I have enjoyed with the house and with Valentino himself. I deeply regret any disappointment caused."
- BANG! Showbiz