But as two exchange students recently discovered in a nightclub bathroom far from home, staring into a stranger's face and seeing your own features staring back is a dizzying and oddly comforting experience.

A bathroom selfie of the near-identical strangers - Ciara Murphy and Cordelia Roberts - went viral when they posted it on Facebook.

The freaky doppelganger phenomenon has long been indulged by literary masters, from Edgar Allen Poe and Mark Twain's The Prince and the Pauper, to the Olsen twins' It Takes Two.

Traditionally considered harbingers of doom, or evil twins, doppelgangers are now the stuff of internet fame.

Like Narcissus staring into a pool of his own reflection, the prospect of body double discoveries has captivated the selfie generation.

"I think I met my doppelganger," British student Ms Murphy and Irish national Ms Roberts wrote on the now-infamous selfie, which found its way to Twin Strangers, a website that facilitates doppelganger searches.

In a YouTube video produced by Twin Strangers, the two women, with matching hairstyles, make-up and black T-shirts, bear a striking resemblance as they describe their chance meeting while on exchange in Bremen, Germany.

The differences in their accents, and the lilt and the pitch of their voices are the only obvious clues that the girls are in fact different people.

Ms Murphy said her fellow classmates often asked her if she had a twin on campus.

"When I was going out at night people started to ask me, did I come here with a sister or a twin and I didn't know what they were talking about … I said no I'm completely on my own out here," Ms Murphy said.

But their questions finally made sense when she came face-to-face with Ms Roberts on a night out.

"Everyone was noticing it and now around college everyone calls them 'the twins'," Ms Murphy's friend Jessica said.

"They're kind of always together now, they're like a package deal.

"I really would like to find my twin stranger … I'm kind of jealous. They have this like bond now just because they look the same," Jessica says in the promotion video that had garnered more than 225,000 views four days after it was posted on Friday.

The website Twin Strangers invites users to log on, upload a photo and nominate facial features in order to find doppelgangers. Users can search photographs of people who have nominated the same facial characteristics.

The site, run by Irish company Vision Independent Productions, boasts other doppelganger success stories, including 26-year-old founder Niamh Geaney, who has been on the hunt for seven of her own doppelgangers since March. She has purportedly found two: fellow Irish national Karen and an Italian woman called Luisa.

With the proliferation of selfies on social media sites like Twitter, Facebook and Instagram, the search for one's twinsta-from-Insta has become a whole lot easier.

In September, 24-year-old Scottish woman Chelsea Marr became an Instagram sensation for her uncanny resemblance to Hollywood actress and director Angelina Jolie - she now has more than 109,000 followers.

Amanda Fisher, a 23-year-old American woman, launched an international search for her doppelganger after she spotted a photo online of a woman who was her spitting image.

But her doppelganger, 22-year-old Meredith Pond, was more frightened and confused than elated to discover a stranger had her face.

Perhaps the old doppelganger folklores still hold some sway.