Jessica Mulroney
Jessica Mulroney's Pippa Middleton moment upstaged Meghan Markle during the royal wedding. Pictured: Prince George, Jasper Dyer, Princess Charlotte, Kate Middleton, Mulroney, Ivy and Florence van Cutsem arrive at the wedding of Prince Harry and Ms. Meghan Markle at St George's Chapel at Windsor Castle on May 19, 2018 in Windsor, England. Getty Images/Jane Barlow

Jessica Mulroney may have stolen the spotlight from Meghan Markle during the royal wedding, according to some fans.

Mulroney caused a buzz on social media following Prince Harry and Markle's big day due to her Pippa Middleton moment. She arrived at St. George's Chapel at Windsor Castle in a tight blue dress by Montreal-based designer Di Carlo couture, which she paired with Christian Louboutin heels.

Mulroney's Pippa moment happened when the Canadian fashion stylist ascended the stairs. She was escorting her twin sons, 7-year-old John and Brian, who were page boys, and the bridesmaids. Unlike Pippa, Mulroney's dress was not white, but many agreed that there were similarities between the two ladies -- at least from behind, Daily Mail reported.

The mother-of-three's derriere didn't escape the attention of netizens. Pippa, who was only 27 when the Duke and Duchess of Cambridge exchanged "I do's" in 2011, also made headlines for the same reason after wearing a tight-fitting Alexander McQueen bridesmaid's dress.

"Sorry guys, #JessicaMulroney stole the show at the #RoyalWedding2018," Laura Hensley wrote on Twitter.

"I totally missed Kate was too busy looking at @jessicamulroney #RoyalWedding," another fan posted.

"I believe Jessica's family stole the show! One of her twins ecstatic smile was the highlight of #TheRoyalWedding Jessica was beautiful & little Ivy was adorable taking MM's bouquet Best Wishes Duchess Meghan MarkleSparkle CaliforniaGirl," another user agreed.

In addition, Mulroney raised some eyebrows when her stylist Rachel Renna shared a snap of her in a gold-embellished outfit for the exclusive after-party. While many agreed that the stylist looked great, others were not impressed because she should not have tried to upstage the bride.

"Jessica Mulroney may well have been trying to have her own Pippa Middleton moment," royal and etiquette expert William Hanson told the Femail. "It is never correct to upstage the bride - whether you are related to them or not. It is every guest's duty to look good but not too good."

Markle and Mulroney are best friends. In fact, according to royal biographer Katie Nicholl, Mulroney helped the Duke and Duchess of Sussex hide their relationship during the first few months of them dating.

"When the story broke, Harry happened to be with Meghan in Toronto," Nicholl wrote (via Express). "He was apparently taken by surprise when his aides called to tell him the story was going to be front-page news and knew that very soon he and Meghan would be under siege."

"A story was leaked that Harry had canceled a flight to Toronto to try and make it look like he was in the UK, but photographers and reporters descended on Meghan's home regardless," Nicholl continued.

Prince Harry and Markle reportedly hid in the Mulroney's plush home.