We're seeing double. 


Courteney Cox wished Jennifer Aniston a happy birthday with a photo of the two of them twinning, right down to Aniston's famed haircut.

On Tuesday, Cox posted a photo on Instagram of herself and Aniston, both in aviator glasses, with Cox seeming to wear a wig that matched her best friend's hair.

"No matter how hard you might try... there’s only one Jennifer Aniston," she wrote. "Happy birthday my dear friend @jenniferaniston! I love you!♥♥♥"

Aniston turned 51 on Tuesday, and previously discussed aging in an interview with InStyle.

"Fifty was the first time I thought, 'Well, that number,'" Aniston says. "I don’t know what it is because I don’t feel any different. Things aren’t shutting down in any way. I feel physically incredible. So it’s weird that it’s all of a sudden getting telegraphed in a way that’s like, ‘You look amazing for your age.’ I think we need to establish some etiquette around that dialogue and verbiage."

Now that most of the Friends cast is on Instagram, we'll be expecting way more birthday posts like this one.