Many are comparing Kate Middleton to her mother-in-law, Princess Diana. From the way they look to their fashion sense and style, one has to admit that the similarities are uncanny. So, is she trying to imitate Prince William's mom?

One old, never-before-seen portrait of Princess Diana seems to prove the claim. Hence, Kate Middleton is strongly urged to "stick to herself" and never try to be somebody else.

Express noted the photo in question was taken by the esteemed photographer David Bailey back in 1988. As soon as it emerged online, many saw its striking similarities with the portraits released to mark the Duchess of Cambridge's 40th birthday in January.

The late Princess of Wales was the epitome of a classic beauty in the snap while looking to the distance. It was the same pose as the future queen consort did in her birthday photo.

They both look "powerful and regal," proving they are indeed two of the most famous and powerful women in recent history. They, too, donned the same one-shouldered gowns, as the image's theme had a similar black-and-white background.

As Princess Diana's photo will be on display at the new royal photography exhibition at Kensington Palace, per ABC News, royal biographer Angela Levin couldn't help but make a tweet, via Express, about the similarities between the two women.

She reminded Kate Middleton that she didn't have to "emulate anyone else." She should just "stick to being herself" and didn't need to try to be somebody else, even if it was Princess Diana.

"She's great as she is," Levin tweeted. Meanwhile, Princess Diana's snap is just one of the several images done during a shoot commissioned by the National Portrait Gallery.

ABC News revealed Bailey kept this particular photograph in his archive and had never been publicized before. In a press release, it was said the People's Princess personally chose the renowned photographer to take her photo after being recommended by several other known photographers to do the commission.

Princess Diana's never-before-seen photo will be just one of the royal family's images that will be seen in the exhibit called "Life Through a Royal Lens." This will explore the royal family's relationship with the camera and give the public a glimpse of them while not on duty.

Historic Royal Palaces curator Claudia Acott Williams said in a statement that photography had shaped how the world viewed the British monarchy ever since Queen Victoria and Prince Albert first embraced this revolutionary technology. It allowed the royal family to give "fascinating insights" into their life and work, changing their royal image and creating and an extraordinary relationship between the crown and the subject.

"Life Through a Royal Lens" will begin on Friday, March 4.