It is always surprising when you think you know a famous face - only to find out that there is someone else out there who shares everything with them, from a birthday, to parents, to even looking absolutely identical! Check out some of the famous faces who have a twin sibling or twin youngsters here...
Ashton's twin, Michael, was born with cerebral palsy, and the actor opened up about him during a speech at the Ron Pearson Centre after receiving the Robert D. Ray Pillar of Character Award. He said: "My brother was born with cerebral palsy and it taught me that loving people isn't a choice and that people aren't actually all created equal. The Constitution lies to us. We're not all created equal. We're all created incredibly inequal to one another, in our capabilities and what we can do and how we think and what we see. But we all have the equal capacity to love one another, and my brother taught me that."
The Casino Royale actress has a non-identical twin sister, Joy, and has said that they couldn't be more different from one another. "Joy and I are very contrasting characters," Eva told the MailOnline. "She never wanted to act, which was quite good because it would have been very competitive between us. We fought and were quite nasty to one another, but now we get on really well. She keeps all the clippings about me."
Jon and Dan Heder
Jon and Dan are identical twins, and the Napoleon Dynamite star opened up to LDS Living about swapping places at school when they were children. "In 6th grade we switched class for an entire day," he said. "His teacher was in on it, but my teacher was an older lady who was a little 'off.' But we paid the price because my teacher gave the kids a quiz which my brother obviously wasn't prepared for. But what did it matter to him? It was my records the poor scores were put onto."
Laverne Cox's brother, M Lamar, appeared in Orange is the New Black as Laverne's character, Sophia, in a flashback before her transition. Talking about the decision to catch M in the role, Laverne told the Telegraph: "We went through an eight-hour hair and make-up process to come up with Sophia's looks through her transition, but Jodie Foster didn’t think I was butch enough to do it myself."
Olly Murs has a twin brother, but the pair have sadly been estranged for several years. The fall out reportedly occurred when Olly missed Ben's wedding due to his commitments on The X Factor. The singer wants to reconcile with his twin, telling the Sun's podcast: "Every artist has a dark side or something that is against them, mine was always my brother. I think there's still a love there between all of us, it's just about finding a resolution and finding that moment in time where you can make it all come together and be fine."
Scarlett is three minutes older than her twin brother, Hunter. The pair co-starred in a film titled Manny & Lo as children before Hunter moved away from acting, and worked on President Barack Obama's campaign back in 2008. He was also the community organiser for Manhattan Borough President Scott Stringer's office.
Will and Rupert seem to have a close relationship, but after they were born prematurely and separated, Will revealed that he struggled from post-traumatic stress disorder. "Now, with twins, they'll wrap them up together, but then they didn't," Will said. "It was pretty heavy. We came to life together and then got pneumonia and was very ill."
Vin posted a rare photo of his twin brother with his friend, the late Paul Walker, writing: "The other guy in the photo is also named Paul... and although they look more alike, he is actually my twin brother."
Celine Dion and Rene Angelil's sons
The Canadian singer gave birth to fraternal sons in October 2010, and named them after two people she greatly admires. Little Eddie was named after Celine's favourite Algerian songwriter Eddy Marnay, while Nelson was taken from Nelson Mandela. Celine and her late husband Rene Angelil are pictured carrying their twins and accompanied by their other son Rene-Charles Angelil.
Jennifer Lopez and Marc Anthony's twins
The Latina beauty and her former husband Marc welcomed fraternal twins, Emme Maribel Munez and Maximilian David Muniz, in 2008. Jennifer is often pictured enjoying quality time with her five-year-old twins, and was even interviewed by them on her YouTube channel in a segment called 'Twin Talk'.
Gisele Bundchen and Patricia
Patricia shares her supermodel sister's good looks, but prefers to stay behind the camera. The blonde beauty has dabbled in modelling, but is now Gisele's manager. The Victoria's Secret angel posted a stunning photo of the pair on Facebook, on their birthday. "I feel so lucky to be born with my best friend," wrote Gisele. "I love you Pati. Happy birthday!!! #birthday#bestfriendintheworld #oldpicture #love #twins."
Angelina Jolie and Brad Pitt's twins
The former couple welcomed twins Knox Leon and Vivienne Marcheline in 2008, with the first official photos of the baby sold to HELLO!. The twins were born in 2008, adding to Brad and Angelina's big brood. The couple have one other biological child together, Shiloh Nouvel, and three other adopted children — Maddox, Pax and Zahara.
Mariah Carey and Nick Cannon's twins
The pop star gave birth to her sons in April 2011, while supposedly listening to her hit We Belong Together. Mariah and Nick named their twins Moroccan and Monroe, and their birthday romantically falls on their parents' wedding anniversary.
Mary-Kate and Ashley Olsen
The child stars found fame after their appearances on various TV shows and films, from Full House to New York Minute, but the Olsen twins are now known for their fashion line Elizabeth and James. Mary-Kate and Ashley are actually fraternal and not identical twins. Speaking about their childhood, Mary-Kate said: "We were always hard workers as kids. It's just the way we are, the way we were raised. Our work ethic was everything, and that never left us." The Olsen twins are thought to have a combined worth of £62million.
Ricky Martin's sons
The Livin' La Vida Loca singer welcomed twin sons Matteo and Valentino through a surrogate mother in August 2008. The adorable boys are often pictured looking just as fashionable as their cool dad.
Rosie Fortescue and Lily
Lily loves the Chelsea life as much as her Made in Chelsea star sister. The brunette beauty is head of wholesale for Austique, the fashion-forward boutique on King's Road.
Shayne Ward and Emma
X Factor winner Shayne has a twin sister Emma, who has supported him throughout his musical career and enjoyed duetting with him as a child. Shayne says that one of his earliest memories is of the pair singing Kylie and Jason's Especially For You for the family one Christmas when they were four years old. Shayne and Emma are pictured at his book signing of Shayne Ward: My Story in 2006.
Siva Kaneswaran and Kumar
The Wanted's Siva has a twin brother Kumar who looks exactly like him, and according to the singer, Kumar likes to make the most of it. "He goes around saying to fans he's me to fool them and they believe him every time," said Siva. "He does a bit of modelling and at a fashion show everyone was shouting my name at him and he was loving it. He gets people taking pictures of him in restaurants and everything."
Sarah Jessica Parker and Matthew Broderick's daughters
The Sex and the City star and her actor husband Matthew delighted fans when they announced they were having not one, but two surrogate babies. Marion Loretta Elwell and Tabitha Hodge Broderick were born in 2009 in Ohio, joining their older brother James Wilkie born in 2002. The little twins always step out looking just as fashionable as their style icon mother, and are often dressed in matching outfits.
Tia and Tamera Mowry
The on-screen stars are best known for their hit show Sister, Sister but the child stars now have their own reality show, Tia & Tamera. In one episode, the pretty twins go to the doctors to find out if they are in fact identical twins, and not fraternal ones. "I'm afraid it's going to say, 'You're not identical,' and that thought really scares me," said Tia on the show. "I would feel like my life was a lie." Tia and Tamera find out that they are in fact identical twins.
Prince Frederik and Princess Mary's twins
The young Prince Vincent and Princess Josephine of Denmark were born in January 2011, joining their older siblings Prince Christian and Princess Isabella. When they left the hospital in their parents' arms, proud dad Frederik lovingly described them as "miracles times two".