Roger Federer's two sets of twins stood out in the crowd as they watched their dad make Wimbledon history on Sunday - for wearing matching outfits.
Girls Myla Rose and Charlene Riva, seven, were dressed in identical flowery dresses.
Boys Leo and Lenny, three, both wore a pale blue jacket, white trousers and the same dark shoes.
Dressing twins in identical outfits is not uncommon among parents, but some experts warn it may not be a good idea.
Keith Reed, chief executive of the Twins and Multiple Births Association (Tamba), says it is important for parents to help multiple birth children develop their own identities.
This can be done by dressing them differently and using their individual names rather than calling them "the twins" or "the triplets".
He adds: "If they are used to always being together or always wearing the same clothes, then the older they get the more distressed they may become if you try to make changes.
"However this does not mean denying their special relationship as one of a multiple.
"Rather it allows them to see themselves as individuals who have the bonus of being part of a multiple unit."
Carla Hallmark, 38, from south-east London, is mum to one-year-old non-identical girls Farrah and Rae.
She says she sometimes dresses her daughters in the same outfits out of convenience.
"We don't really think about it. It's literally go into the shop and buy two of those, two of those and two of those.
"If the girls were identical I think my view would be very different. Our two look so different, so for me it wasn't really a problem and I decided it for ease.
"It's simply about getting up in the morning and going to their wardrobe and grabbing two of those and two of those. It's not a conscious decision to dress them the same every day.
"Yes it's quite cute and I don't dislike the way it looks but it really it is about ease. I don't think it really matters until they get to an age where they tell you what they are not going to wear.
"For now, while we are trying to get them out of the door in 15 minutes in the morning, it's certainly for ease."
But for some parents of twins, they have made a conscious decision not to dress their children in matching or identical outfits.
PR director Marc Cohen, 37, from north London, is a dad to seven-year-old identical twins Izzy and Heidi.
He says: "Everyone is different but for us it's hard to get our heads around why anyone would want to have kids dressed the same, particularly if they are identical.
"They have their own personalities and they're their own people and from such an early age to have them dressed the same removes quite a lot of their personality.
"It does present challenges. I can understand if you've got a lot of kids it might be easier to be dressing them the same way.
"But as they get older it's really hard to encourage their individuality with identical twins, so I think it's worth working that bit harder to give them their own personalities."
Lauren Apfel, editor of online parenting magazine Motherwell and mum of twins Phoebe and Jasper, six, is against dressing twins the same and says parents tend to do it because it is considered "cute".
"People are fascinated by twins, and they love seeing them as an adorable diptych. But this is more about appearances than what is actually best for the kids themselves," she adds.
"Twins will always have a special bond. Dressing them differently doesn't do damage to that possibility.
"Rather it is an important step towards allowing them to thrive as individuals within their sibling relationship, as opposed to their identities being dominated by it."
Clinical psychologist Linda Blair, who has written a book exploring sibling relationships, says there is a fascination with multiple births and parents often try and "enhance the attraction" by making their children look alike.
But she warns it can have a negative impact on the children themselves and their relationship with their sibling.
"Children want more than anything to be seen as special in their parents' eyes, as different from everyone else.
"When you duplicate them, you're not going to harm them in some kind of long-term way, but what you're doing is putting the warmth of their relationship at risk.
"The person they are going to want to compete with and push away is the person who is most like them.
"So it isn't good for the sibling relationship to dress them alike and put them in one box.
"The best way to raise confident kids is to continually praise and be proud of their differences and uniqueness."
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