People can't get over how much Reese Witherspoon's daughter looks like her

People can't get over how much Reese Witherspoon and her daughter Ava Phillippe look alike.

It's been no secret that the Big Little Lies star and her daughter are essentially carbon copies of one another, but people are shocked all over again after seeing the actress celebrate Ava's 23rd birthday.

Reese, who shares Ava with her ex-husband Ryan Phillippe, shared a post to Instagram to pay special tribute to her lookalike, and fans only had one thing on their minds.

The picture of the mum and daughter duo smiling together on the beach would make you do a double take, and Reese's followers were inclined to agree.

She captioned the snap: "Happy Birthday to my favourite daughter, Ava !! Every day that I get to watch you become the most amazing woman is such a gift.

"Your gigantic heart, generous spirit, and endless creativity inspire me every day. I love you so much."

People were gobsmacked over the resemblance, which seems to grow more and more uncanny as Ava grows older.

Commenting on Reese's birthday post, one follower joked: "You birthed your identical twin."

A second admitted: "I will never not do double takes at this duo."

And a third wrote: "That’s not even normal how exactly alike you look. Kudos for good genes."

Accompanying the hundreds of comments from fans, Reece's celeb pals like Julianne Moore, Zooey Deschanel, and Cindy Crawford took the opportunity to share their birthday wishes.

Thanking her mum for the special shoutout, Ava commented: "Okay I know I’m biased but... you really do ‘mom love’ like no one else can. Thank you for celebrating me as I am since day one."

She added: "Also, I know I technically have to be your favourite daughter considering there’s no competition... but I don’t think I’ll ever get tired of hearing it!"

As if those two couldn't get any cuter!

Over on her own Instagram account, Ava is often showered with pretty similar compliments from fans, raving about how much she looks like her mum.

The comparisons were especially heavy back in April when Ava posted a snap from the red carpet, dressed to the nines in a hot pink dress.

As you can only imagine, it didn't take long before the Legally Blonde comments started rolling in.

"No she looks so much like her mum", wrote one follower.

"Wow you look just like that one girl from Legally Blonde", joked another.