She posted a bikini photo taken with BFF Larsa Pippen on Monday.

But Kourtney Kardashian was clearly feeling nostalgic Tuesday as she shared yet another bathing suit snap from her teenage years.

In the photo, a 14-year-old Kourtney posed upon a balcony in a black-and-white striped bikini.

'14 years old': Kourtney Kardashian posted a throwback bikini photo taken from a vacation with Kim Kardashian on Tuesday 
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’14 years old’: Kourtney Kardashian posted a throwback bikini photo taken from a vacation with Kim Kardashian on Tuesday

’14 years old,’ she wrote in the caption.

Kim had previously posted a photo from the exact same vacation.

The photo was of Kim at around age 12, and showed the future reality star posing outside on the balcony in a summery white bikini.

On Sunday night viewers watched as Kourtney laid into her sister on their show, during a trip to Japan filmed earlier this year.

Throwback: The photo was of Kim at around 12-years-old, and showed the future reality star posing outside on the balcony in a summery white bikini
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Throwback: The photo was of Kim at around 12-years-old, and showed the future reality star posing outside on the balcony in a summery white bikini

Their plan was to shoot a  Yeezy campaign – using paparazzi photos – with the  clothes designed by Kim’s husband Kanye West.

They had a few days to shoot 20 looks, which would all be modeled by Kim.

On arrival Kim was busy getting the fans to shoot her in Kanye’s outfits, while her sisters wore their own choice of  clothes – which Kim called ’embarrassing’.

Kim and Kourtney Kardashian go shopping with the kids in NYC

BFFs! Kourtney posed in a black and white bikini alongside gal pal Larsa Pippen on Monday

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BFFs! Kourtney posed in a black and white bikini alongside gal pal Larsa Pippen on Monday

‘They’re just like completely clashing and making my  outfit look really bad and they’re ruining everything,’ she griped, as she tried to make them walk separately from her.

‘I think Kim is just being rude,’ sighed Kourtney.

‘I don’t care…if you can’t take the criticism you shouldn’t have come on this trip,’ shrugged Kim.

‘Your f***ing outfits suck, you’re wearing a puffy vest, pink hair and turquoise  shoes,’ snapped Kourtney.

Before the trip Kim was nervous about pleasing her rap star husband and they planned the outfits together meticulously.

Kourtney Kardashian before she arrived at the studio for reality show

The plot thickens: On Sunday night viewers watched as Kourtney, pictured Monday, laid into her sister on their show, during a trip to Japan filmed earlier this year
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The plot thickens: On Sunday night viewers watched as Kourtney, pictured Monday, laid into her sister on their show, during a trip to Japan filmed earlier this year