"American Horror Story" co-creator Ryan Murphy has explained the grueling process to turn Sarah Paulson into a two-headed woman for the newest installment of the FX anthology series titled "Freak Show."

During a conference call earlier this week, Murphy said that producers were not initially certain if they could actually pull off a neat look of conjoined twins Bette and Dot Tattler, who are both played by Paulson.

"Most people who do conjoined twins do something where they connect them at the chest and you historically have two actors playing those different parts," Murphy said, according to The Hollywood Reporter. "I really wanted Sarah to be both roles because I thought that would be more challenging. We did a test early on that was good, but I didn't love it. I thought if we kept working on it, it would get better  - and it did."

"We have a prosthetic head for Bet and Dot," explained the 48-year-old director and screenwriter, according to E! News. "She will record her dialogue with an earwig so she literally has to do scene with herself. She is so dedicated, she didn't want someone off camera to do it. We do that and we change the head. And that is the close shot. And then you have to do it all over again for a master. And then all over again for the green screen. So it's very very time consuming."

Scenes with the Tattler sisters take 12 to 15 hours to film, while an average scene only takes five hours to complete, THR noted.

But Murphy said that Paulson, 39, loves playing the conjoined twins so much that "she has never lost the faith."

"It's really two people with different attitudes and facial expressions," Murphy said of Bette and Dot. "She has to be left handed and right handed, she has to learn how to walk in a special way. And it's one of the best things, if not the best thing she's ever done. It's the most challenging thing I've ever seen any actor do ever."

In an interview with USA Today, Paulson opened up about how she plays the conjoined twins differently.

When playing Dot, she said that she tries to keep her face "as still as possible because she's not as welcoming of other people in the world and doesn't want to telegraph what she feels as much."

Bette, on the other hand, is more expressive and warm. "Bette just wants to hug everyone and be near everyone. She is much more open," Paulson explained.