At first glance this selfie might look like a mirror image.

But the snap is actually of identical twins Emma O'Neill and Catherine Caudwood, who look so alike even their own boyfriends struggle to tell them apart.

The sisters, from Durham, love turning heads so much that they still co-ordinate their outfits and hair when they go out together - even though they are 25.

Seeing double: Twin sisters Catherine (left) and Emma, both 25, used to fool their school teachers by attending each other's classes instead of their own

Inseparable: Catherine, left, and her twin are 'best friends' and live just five minutes' apart

Mirror image: The pair are so alike (Catherine is seen on the left and Emma on the right) they are regularly stopped in the street, and they've now launched an Instagram account

Emma, a technical support worker, said: 'We were always dressed the same when we were young. We would either be in completely matching outfits or I would wear something blue and Catherine would wear the same outfit in pink.

'Because we were twins a lot of people bought us identical outfits too.'

The sisters, who live five minutes' away from each other, took advantage of their similarities to swap lessons in school.

Emma said: 'If there was certain classes I didn't want to go to, Catherine would go instead and I would go to hers. We didn't get found out until someone told the teachers.'

Sainsbury's worker Catherine added: 'The only thing was that I wore glasses, so Emma had to wear them to pretend to be me.

'She couldn't see a thing in them, and I couldn't see a thing without them!'

Playing tricks: Emma, left, and Catherine say even their boyfriends struggle to tell them apart

The sisters, seen left in a Snapchat picture, share the same clothes, hairstyles and make-up

They still wear similar outfits to the gym and nights out, and strangers are so stunned they sometimes stop the pair on the street.

Catherine added: 'We are often told our mannerisms are the same, which I think is why people find it hard to tell us apart.'

Even their loved ones can struggle to tell them apart.

Emma said: 'When our mother remarried we were both bridesmaids and I was dating my now-husband at the time.

'Our outfits, hair make-up and accessories were identical and I'd only been with James for a couple of weeks so he couldn't really tell us apart.

Twice as nice: The sisters were dressed in matching outfits as children as still enjoy it

Angelic: Emma, left, and Catherine, right, look adorable in matching green dresses

'He was really uncomfortable and didn't want to show one of us affection in case he got the wrong one. He just kept his hands in his pockets and his head down throughout the wedding.'

The pair have recently launched an Instagram account to connect with other twins around the world. But for all their similarities, the pair have their own interests.

Emma said: 'We both enjoy going to the gym, but I'm definitely more of a tomboy.

'I love Marvel, action films, playing on my Xbox and I've always been into rock music whereas Catherine is more into dance.'

Catherine said: 'We don't really have the same taste in fashion but Emma always does my hair and make-up for a night out.'