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While we'd like to think that we're all unique, it's likely that somewhere in the world there is at least one other person that bears a striking resemblance to you - and celebrities aren't immune to these odds.

In fact, there are several celebrities that could pass as twins, with similarities in hair colour, style or facial features all adding to the doppelganger effect.

From Katy Perry and Zooey Deschanel, to Tom Hardy and Logan Marshall-Green, FEMAIL looks at the celebrity pairs that might make you do a double take. 

1. KEIRA KNIGHTLEY & NATALIE PORTMAN 

Keira Knightley, 30 (left), and Natalie Portman, 34 (right), bear a striking resemblance to each other

With dark hair, doe-like eyes and lithe frames, it's no wonder that many struggle to tell the difference between British actress Keira Knightley, 30, and her celebrity twin, American Natalie Portman, 34. 

At the age of 12, Knightley was hired due to her close resemblance to Natalie Portman, who had secured the role of Queen Amidala's in Star Wars: Episode I - The Phantom Menace.

Knightley played the part of Queen Amidala's handmaiden Sabé, and reportedly many people had trouble telling them apart when they were in full costume. 

2. TOM HARDY & LOGAN MARSHALL-GREEN 

Tom Hardy, 37 (left), and Logan Marshall-Green, 38 (right), mirror each other's looks 

British actor Tom Hardy, 37, has paved his way in Hollywood with a string of macho roles in blockbuster films such as Inception and The Dark Knight Rises.

But it turns out that the actor's 'tough guy' aesthetic isn't as unique as he would like to think, with American actor Logan Marshall-Green, 38, mirroring his looks, and only a year older.

Although sharing the same dark hair, brooding face and rugged facial hair, Marshall-Green has - so far -had comparatively less success in the acting industry, with notable credits only extending as far as Prometheus and The OC.

3. KATY PERRY & ZOOEY DESCHANEL 

Many have commented on the similarities between Katy Perry, 30 (left), and Zooey Deschanel, 35 (right)

Many style watchers have commented on the striking resemblance between singer Katy Perry, 30, and actress Zooey Deschanel, 35.

It's not hard to miss the small facial features, piercing blue eyes and jet-black locks that have helped both secure successful careers in their image-obsessed industries

While Perry is used to sticking to what she knows behind the mic, New Girl actress Deschanel is known for dabbling in a bit of both, also starring in the She & Him music act with singer M. Ward.

4. DANIEL RADCLIFFE & ELIJAH WOOD

Daniel Radcliffe, 26 (left), and Elijah Wood, 34 (right), are similar in height, eye and hair colour

Both actors became instantly recognisable due to roles in highly-anticipated film franchises: British Daniel Radcliffe, 26, as Harry Potter and American Elijah Wood, 34, as Frodo in Lord of the Rings.  

Both with bright blue eyes, dark crops of hair and similarities in height - Radcliffe is 5ft 4in and Wood is 5ft 5in-  the similarities are striking.

5. ISLA FISHER & AMY ADAMS

Isla Fisher, 39 (left), and Amy Adams (right), 40, are spitting images of one another

Golden Globe winner Amy Adams, 40, is known for her breakout roles in films such as The Fighter and America Hustle, whereas Isla Fisher, 39, is better known for her comedic parts in chick flicks such as Confessions of a Shopaholic and Wedding Crashers.

But what both actresses have in common is their uncanny similarities in looks.

Both with enviable wavy red locks, pale skin and petite features the pair have been compared to each other over and over again. 

6. MILA KUNIS & SARAH HYLAND 

Mila Kunis, 31 (left), and Sarah Hyland, 24 (right), share such similarities in looks, they could pass for each other's sisters

Actress Mila Kunis, 31, has enjoyed a lengthy career, including roles in Black Swan and Jupiter Ascending, but she may soon have competition in the form of doppelganger, actress Sarah Hyland, 24.

Hyland has so far only enjoyed roles in series such as Modern Family and a small part in Scary Movie 5, but her career is undoubtedly on the rise, with a film role in horror flick Satanic coming up in 2015.

With dark hair, exotic slanted eyes and plump youthful faces, the pair could perhaps pass for sisters.

7. MATT DAMON & MARK WAHLBERG 

Matt Damon (left), 44, and Mark Wahlberg (right), 44, regularly get mistaken for one another 

Mark Wahlberg, 44, has had starring roles in iconic films such as The Fighter and The Departed.

Matt Damon, 44, scored an Oscar and Golden Globe due to his screenplay for Good Will Hunting and has enjoyed much success from the Bourne films.

It's safe to say both actors have enjoyed well-respected and illustrious careers in acting - but this doesn't stop fans from mistaking one for the other.

Damon admitted to Absolute Radio: 'I've talked to Mark about this because he gets people [that] come up and say, 'I love you in The Bourne Identity. 

'So Mark and I have a deal. If we're mistaken for one another, we have to be as polite as possible.'  

8. ZOE SALDANA & JADA PINKETT-SMITH 

Zoe Saldana, 37 (left), and Jada Pinkett-Smith, 43 (right), could pass as sisters

Zoe Saldana, 37, is only 43-year-old Jada Pinkett-Smith's junior by six years, and the two could pass for sisters.

But where Pinkett-Smith's acting career has taken somewhat of a backseat - having only secured a handful of film credits in the last couple of years - Saldana's is on the up, with a recent lead role of Guardian's of the Galaxy and filming for the next three Avatar films underway.

MORE CELEBRITY TWINS...

Jurassic World actress Bryce Dallas Howard, 34 (left), and Zero Dark Thirty lead, Jessica Chastain (right), 38, bear a striking resemblance to one another, especially with their flame-coloured hair

Australian Wolf of Wall Street star Margot Robbie, 25 (left), could be sisters with American My Name Is Earl actress Jaime Pressly (right), 37, despite their 12-year age-gap

Spanish Skyfall villain Javier Bardem (left), 46, and American Watchmen actor Jeffrey Dean Morgan (right), 49, almost look like twins

The OC actress Rachel Bilson, 33 (left), and pop star Selena Gomez, 23 (right), share similarities in looks due to their dark hair and youthful faces