10 stars who are often mistaken for other stars

When you approach a celebrity for a photo or an autograph, make sure it's the right celebrity.

In a new video from Vanity Fair, a number of stars revealed the strange things their fans tell them when they meet in person. According to Jennifer Garner, she hears "Oh my god, you’re so much prettier in person" a lot.

But what was even more surprising were the number of stars mistaken for other stars.

Here is a run down of the famous faces people often think are other famous faces:

Keira Knightley and Anne Hathaway/Natalie Portman

British actress Keira Knightley told Vanity Fair that a fan wouldn't believe her when she said she wasn't Anne Hathaway, but more often she gets another Oscar winner.

“Natalie Portman I get a lot, and I get chased through airports,” she said on "The Graham Norton Show" earlier this year. “I feel quite sorry for her because she must get chased a lot because it’s happened like five times where someone’s been like, ‘Natalie! Natalie! Natalie!’ And I’ll sign and take a picture as Natalie.”

Jennifer Connelly and Demi Moore

"Noah" star Jennifer Connelly says she is often mistaken for another raven-haired actress. She told VF she often hears: "It’s Demi Moore!" Though Moore is eight years older than Connelly, both actresses were teen stars.

Steve Carell and Stephen Colbert

Though you could argue that actor Steve Carell is actually more famous than who he is mistaken for, it happens nonetheless. "Stephen Colbert. Love you," he gets, Carell told Vanity Fair. Colbert was actually Carell's understudy at Chicago's Second City, before the two of them appeared on "The Daily Show" together.

Zooey Deschanel and Katy Perry

Zooey Deschanel should probably put her singing career on the back burner if she doesn't want to be mistaken for Katy Perry anymore.

"It's a little bit annoying, to be totally blunt," the "New Girl" star told MTV in 2009. "The only similarity that we have is that we look a little bit alike."

Daniel Radcliffe and Elijah Wood

He may be the most famous young actor in the world but not everyone recognizes Daniel Radcliffe when they meet him. Harry Potter told GQ in 2011 that he is "constantly" mistaken for Frodo Baggins.

“I was in Japan and someone held out a photo of him for me to sign. I couldn’t say it in Japanese so I wrote, ‘I’m not Elijah Wood but thanks anyway, Daniel Radcliffe,'" he said. “If I was a bit more puerile I would have written ‘The Lord Of The Rings is rubbish.’”

Amy Adams and Isla Fisher

Amy Adams has carved out a very recognizable career with roles in "The Fighter," "The Master" and "American Hustle," yet she continues to be mistaken for a Shopaholic.

"I get Isla Fisher all the time, still," Adams told Vanity Fair earlier this year. "And I know Isla, and for a while our kids went to the same dance school. When I'm with Isla, we both look at one another and, ‘I get it, but I don't get it.'"

Chad Smith and Will Ferrell

Perhaps the most often confused two celebrities in America are "Anchorman" star Will Ferrell and Red Hot Chili Peppers drummer Chad Smith. The latter told Rolling Stone in 2011 that when the duo met at the premiere of "The Ladies Man" in 2000, Ferrell said, “You’re very handsome.” The two men once even held a a drum-off for charity on "The Tonight Show with Jimmy Fallon."

Meryl Streep and Glenn Close

In 2012, Meryl Streep poked fun at the New York Times blogger Melena Ryzik for constantly pitting her against lookalike Glenn Close. “On behalf of Glenn Close and me, who are often mistaken for each other, there should be no illusions,” Streep said. “I adore her, and I adore her film.”

Matt Damon and Mark Wahlberg

During a Reddit AMA earlier this year, Matt Damon confessed that he is often mistaken for fellow Bostonian Mark Wahlberg.

"I do get confused with Mark Wahlberg a lot, and we just have a deal that whenever we get mistaken for each other we have to be very polite," Damon said. "Can’t give the other a bad name."

Wahlberg stuck to the deal when a fan mistook him for Damon in 2013, posting the fan photos on Facebook and writing, "Close enough."

Elizabeth Banks and Chelsea Handler

In 2012, "Hunger Games" star Elizabeth Banks said she hides behind the fact that fans mistake her for Chelsea Handler. “I don’t mind being compared to Chelsea Handler at all. It helps me when someone says, ‘oh, you’re Chelsea Handler’ and I say ‘yes I am.’ That gives me one more gain of anonymity,” Banks told  FOX411’s Pop Tarts. “We met at a party and we were both aware people compared or confused us. She’s a great broad, a real wit.”