"I'm not one to hold onto things built this was a damn good purchase!"
Cox's soon-to-be 15-year-old daughter, Coco Arquette, is seen on the right, while Cox - wearing the same outfit during a red carpet event 21 years prior - is seen on the left in the image.
In the caption, she mused on the neat moment.
Cox's "Friends" co-star Lisa Kudrow commented "Oh wow..." while her ex-sister-in-law Rosanna Arquette said, "Oh wow".
Many fans were quick to point out that Courteney recycling her dress 21 years later for her daughter aligns with her Friends character Monica Geller.
Courteney wore the dress to the Hollywood premiere of the casino thriller Snake Eyes, an event she attended with Coco's father David Arquette.
Cox often posts praises for her daughter on her Instagram account.
"I want her to tell me everything, and she doesn't want to tell me anything", Cox said.
Within the next two years, the divorce was finalized, and Courteney has spent almost the past half-decade engaged to Snow Patrol's Johnny McDaid. We bicker, let's be honest, but we love each other.
"I would also describe it as, well, I am a 13-year-old girl, you are a mom, so I love you, but of course we're gonna get in fights".