Margot Robbie wanted Emma Mackey to be in 'Barbie' so she could joke about them being lookalikes — but the joke was cut

• "Barbie" almost contained a joke about how Margot Robbie and Emma Mackey look alike.
• Robbie told BuzzFeed it was scrapped once they saw each other on set with different colored hair and decided they didn't look that similar.
• The actor says she gets mistaken for Mackey all the time.

"Barbie" star Margot Robbie knows she and "Sex Education" star Emma Mackey share a resemblance, so much so that she thought it would be fun to play it up in Warner Bros.' upcoming film based on the Mattel doll.

"She plays one of the Barbies in the movie pretty much because Greta and I thought it would be funny," Robbie told BuzzFeed of her discussion with "Barbie" director Greta Gerwig.

"We were gonna do this whole joke about us looking similar," Robbie added.

The joke got scrapped after Robbie and Mackey saw each other on set and decided they didn't look as identical as they previously thought.

Mackey isn't sporting blonde locks in the "Barbie" movie, which makes it easier to tell the two stars apart.

"Once we got all dressed up as our Barbies, we were kind of like, 'We don't actually look that similar,'" Robbie said. "So, we didn't put that joke in the movie."

But Robbie said she gets fans who mistake her for Mackey all the time. Instead of correcting them, she just rolls with it.

"When people come up and say, 'I loved you in 'Sex Education,' I just say 'Thank you. Thank you so much,'" Robbie said.

"Barbie" is out in theaters on July 21.