Kate Middleton attends an event wearing an Alice Temperley dress previously worn twice.

The Duchess of Cambridge stepped into the red carpet Wednesday for the premiere of David Attenborough's film "Natural History Museum Alive 3D" wearing a black lacy dress by Alice Temperley.

Various sources, however, noticed that this was not the first time the Duchess wore the said dress -- in fact it was worn on two more occasions last year. The first was during the premiere of "War Horse" in London last January, and the next was during a fundraising activity at her alma mater St. Andrews ten months later. This time around, Kate was not carrying anything with her; unlike last year where she was carrying a clutch purse.

Before the screening, she and her husband Prince William stopped by to chat with some of the guests. Kate, in particular, approached some of the children present in the venue. As Kate and Prince William took their seats before the screening started, they both put on their 3D glasses given the film is in 3D format.

Earlier this week, designer Alice Temperley gushed to the UK Telegraph about making clothes for Kate and her sister Pippa. She keeps mum about the details, but the designer describes the sisters as 'lovely girls.'

'The Duchess is an inspiration,' says Alice. 'She's very graceful, gracious and she's a brilliant ambassador for British fashion. She mixes up designer and high street; the perfect modern-day woman.'

Kate and Pippa have been regularly wearing Temperley dresses on numerous occasions. Aside from the black lacy dress she has worn thrice recently, Kate wore a similar but shorter black lacy dress at a SportsAid event last month. On the other hand, Pippa famously wore the emerald green backless dress that Temperley made for her sister's wedding reception in 2011.