Khloe and Kim Kardashian In the Same Plunging White Dress -- Who Wore It Best?

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Khloe Kardashian is looking slimmer than ever.

It's a sister showdown.

Khloe Kardashian stepped out to the Opening Ceremony and Calvin Klein launch party last Thursday in Los Angeles to support her younger sis Kendall Jenner -- the new face of Calvin Klein Jeans  -- where she looked slimmer than ever in a curve-hugging white Wes Gordon dress. Featuring a plunging neckline and a high slit up the middle of the long-sleeve design, it's safe to say the 30-year-old reality star turned plenty of heads.

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But if the dress looks familiar, there's a reason. Her older sister Kim Kardashian wore the same exact dress almost a year ago, and posted this glam pic on Instagram.

"Fashion moment with my mamma @krisjenner," she wrote.

Khloe has definitely been working on her fitness lately, and she shared the results with her fans with a selfie of her impressively slim stomach in February.

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"Looking back at pictures of myself I didn't realize at the time how unhealthy my lifestyle actually was," she wrote about the side-by-side comparison of her noticeable weight loss. "People love to call me the fat one but as weird as it sounds I still don't think I would consider myself fat back then. Definitely overweight and unhealthy, yes. About two years ago I decided to turn to fitness as a form of therapy and as a stress reliever. I started slow and eventually I started working out 4 to 5 days a week. We all have to start somewhere and doing something is better than nothing at all."

Looking good, Khloe!