Is Kate Middleton trying hard to be everyone else but herself? This is somehow implied by a royal biographer when new, unseen photos of Princess Diana emerged and one of the comments these garner was that there are strong semblances between Diana and Kate.

There has been much discussion about the strong resemblances between Diana's previously unseen photo taken by the famous photographer David Bailey in 1988 and the photo of Kate Middleton released to celebrate her 40th birthday this year.

However, a royal biographer believes caution should be taken in lauding her similarities with Princess Diana, lest Kate Middleton continues on not having her own personality.

The never-before-seen Diana photo depicts her staring out into the distance. Kate Middleton has the same kind of portrait, depicting her to be both strong and regal at the same time.

Coincidence or not, both photos have a black-and-white theme, and both ladies wore one-shouldered gowns.

According to royal biographer Angela Levin however, the Duchess of Cambridge doesn't need to copy anybody else. It's not clear where she got the idea that Kate was merely copying Princess Diana though.

The Duchess of Cambridge should try harder to be her own fabulous self.

"I think Catherine, Duchess of Cambridge should stick to being herself. She doesn't need to try to be someone else including Diana. She's great as she is," she said.

This is hardly the first time that it was implied that Kate Middleton does not have a unique personality. In fact, the statements made in the past were so much more brutal.

Take the comment of English writer Hilary Mantel. The writer likened the Duchess of Cambridge to a mannequin - just pretty and perfect, but no real identity.

While giving a lecture at the British Museum, Mantel described Prince William's wife as someone who's completely different from Princess Diana, because the latter was so human while Kate was so...not.

"Kate seems to have been selected for her role of princess because she was irreproachable: as painfully thin as anyone could wish, without quirks, without oddities, without the risk of the emergence of character. She appears precision-made, machine-made: so different from Diana, whose human awkwardness and emotional incontinence showed in her every gesture," she said.

Mantel even described Kate Middleton as a jointed doll on which "certain rags are hung."