On Sept. 15, the King's office at Buckingham Palace wished Prince Harry a happy 40th birthday on Instagram, X and Facebook, using a photo of the Duke of Sussex taken in Ireland in 2018. Prince William and Kate Middleton's team reposted the same shot on the Instagram Stories of their official shared Instagram and X account, along with another message celebrating Harry's milestone birthday.

While a solo shot of Prince Harry was used in the royal family's official well-wishes on Sept. 15, a closer look shows that the Duchess of Sussex, 43, was actually sitting beside Prince Harry in the larger frame, taken when the couple stopped at Dogpatch Labs in Dublin in July 2018, just two months after their royal wedding that May.

It appears that photographer Jimmy Rainford released two versions of the picture for Getty Images. In one shot, the wider frame showed the newlyweds smiling alongside others. In a separate shot, the closer crop zoomed in on the Duke of Sussex, which seems to be the image used alongside messages for Harry's 40th birthday.

The picture of Prince Harry used across both sets of well-wishes showed him smiling and laughing in a gray suit with white shirt. The photo was taken during the couple's tour of Ireland, their first overseas trip as a married couple.

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Meghan Markle and Prince Harry visit Trinity College in Dublin, Ireland on July 11, 2018.

According to The Independent, Buckingham Palace confirmed via a spokesperson that the image used was not altered and was used in the format it was received, meaning that Meghan was not cropped out of the shot.

Two years had passed since the royal family last mentioned the Duke of Sussex on social media back in 2022.

The same picture was circulated with slightly different wording online. "???? Wishing The Duke of Sussex a very happy 40th birthday today!" King Charles and Queen Camilla's office captioned the snap, while the Prince and Princess of Wales wrote, "Wishing a Happy 40th Birthday to the Duke of Sussex."

Jimmy Rainford - Pool/Getty

Prince Harry and Meghan Markle visit Dogpatch Labs in Dublin, Ireland on July 11, 2018.

PEOPLE understands the Duke of Sussex marked his milestone birthday on Sept. 15 with a private celebration in Montecito, California, surrounded by family and friends. Prince Harry was then expected to continue the festivities abroad with close friends.

The Duke and Duchess of Sussex relocated to her home state in the U.S. after stepping back from their royal roles in the U.K. in 2020, and reside in Montecito with their son Prince Archie, 5, and daughter Princess Lilibet, 3.

Netflix/Youtube (From left) Princess Lilibet, Prince Harry, Prince Archie and Meghan Markle in an image shared in the docuseries "Harry & Meghan," released on Netflix in December 2022.

Related: Prince Harry Says He's 'Excited' to Turn 40 in Birthday Message: 'A Fresh Perspective on Life'

The celebratory posts about Prince Harry's birthday from King Charles and Prince William arrived as a surprise, as public birthday wishes are usually reserved for working royals. However, there have been exceptions, like when King Charles, Queen Camilla, Prince William and Princess Kate wished Meghan a happy 41st birthday in August 2022. In another example, the Royal Family handle (then run by Queen Elizabeth's office) wished Prince Andrew a happy 60th birthday on X in February 2020 after his step back from royal duties in light of outcry around his BBC Newsnight interview in November 2019.

Amid the ongoing rift between Harry and William, as well as the Duke of Sussex's strained relationship with their father, many interpreted the unexpected birthday messages as a potential olive branch.

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King Charles and Prince Harry walk behind Queen Elizabeth's coffin on Sept. 14, 2022.

Heading into a new decade, Prince Harry told PEOPLE that he is focused on fatherhood.

"The best gift I’ve ever been given is, without doubt, my kids. I enjoy watching them grow every single day and love being their dad," the Duke of Sussex told PEOPLE before his birthday in a statement via his spokesperson.

Looking ahead on the calendar, the duke is expected to travel to New York City later this month on behalf of several causes close to heart, including the organization behind Princess Diana's legacy award.