Meghan Markle took everyone by surprise when she walked down the aisle on Saturday in a Givenchy dress designed by Clare Waight Keller.
But some Twitter users reckon they had seen the same design somewhere before - on Jennifer Lopez.
People said the Duchess of Sussex's gown reminded them of the dress J-Lo wore in 2001 film The Wedding Planner, pointing to the similar elegant off-the-shoulder neckline.
"Anyone else get JLO in the Wedding Planner vibes from Meghan Markle ’s dress?" one Royal Wedding watcher asked.
A second wrote: "@JLO I'm a Huge fan of yours. I'm watching the Royal Wedding. Meghan, Duchess of Sussex. Her dress was beautiful.
"Simple & elegant design by Givenchy....but I said to myself, I've seen that design before. Jennifer Lopez wore it in the movie, The Wedding Planner..a shorter version."
However, others said the only thing that is similar is the boat neckline. With one adding, "JLo wasn't the first, Meghan won't be the last. No copying required.”
Meanwhile, the designer of Meghan's dress has spoken of her pride in being involved in such a "historic moment".
Birmingham-born Clare Waight Keller was told by Meghan, who paired the dress with Queen Mary's tiara, in early January that she was the chosen designer.
She said: "It was an extraordinary moment when she told me.
"Of course it's an incredible thing to be part of such a historic moment."
Ms Waight Keller said the process was collaborative, adding: "I think she had very much seen my work and knew what I did.
"I think she loved the fact that I was a British designer, and working in a house such as Givenchy which has its roots in a very classical, beautiful style."
