Kate Middleton's Alexander McQueen dress stumps the internet

Can you spot the difference between the two gowns? Photo / Getty Images

When the Duchess of Cambridge arrived at the National Portrait Gallery on Tuesday night in a striking Alexander McQueen gown she left onlookers stunned.

But it wasn't just because the floral dress was a show stopper. It also bore a striking resemblance to the dress she wore to the BAFTAs in 2017.

The original dress, however, boasted a Bardot neckline while this week's version appeared to be reworked with a cap sleeve.

The 2019 version of the dress, and Kate in 2017 at the BAFTAS. Photos / Getty Images

Eagle-eyed royal watchers noticed this wasn't the only difference and pointed out that the flowers on the two dresses didn't line up the same. It appeared either the entire top section had been replaced, or perhaps it was a completely different dress?

Twitter user "biblio" took to the platform to explain how this might have come about: "It's deconstructed then they make a new bodice either out of spare or original material and attach to the original skirt. Very clever work from her seamstress and great way to save money and get more wear out of the dress."

Others speculated that the Duchess may have simply commissioned an almost identical version of the original dress from Alexander McQueen's Resort 2016 collection.

Another Twitter user noted that the fit looked slightly different: "There was also a distinction if you looked closely at the print on the bodice; while it is the same as that used in the BAFTA gown, it is placed differently from the way it sits on the original dress."

Another pointed out the same thing: "Quickly glancing, the flower placement across the bust doesn't appear to match on both.. anyone else agree?"

However, others believed the mismatched flowers went further than just the bodice.

"The top bodice piece above the thigh area must be one piece," one tweeted. "That's completely different but the below the lower sash matches up."

There's also a possibility the original gown was loaned from the designer, and Kate's stylist simply contacted the designer to borrow the dress, or a similar version again.

"I'm thinking two dresses were made for her and she selected the other one but decided she wanted to wear the other version now because she liked both," one Twitter user suggested.

Twitter user What Kate Wore added: "It also looks like the skirt could be different as well, which would mean this isn't a reworked gown, but a new piece."

Either way, we think Kate looked amazing in both gowns.