Christa Tsao just wanted to get some fresh air with her Australian Shepherd dog Poseidon, but what she experienced in the park that day was beyond her wildest dreams.

She and Poseidon entered the beautiful park, where another dog seemingly suddenly tried to attack her pet.

A couple came to see if she and Poseidon were okay – and the pair then admitted that they actually thought Poseidon was another dog they regularly saw at the park.

Just then, the other dog in question – whose name is Abbie – wandered up, and the owners of the lookalike pups got to chatting.

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The goosebump-inducing moment came when the pet parents took a closer look at the animals side by side.

The resemblance was actually quite uncanny – same coat pattern, same size, and even the exact same birthday!

When the pet owners got to talking, they soon realized that both dogs came from the same breeder and the same litter. (Does anyone else suddenly feel compelled to watch The Parent Trap?)

A TikTok video of the incredible and touching chance encounter immediately went viral, with hundreds of thousands of people watching as brother and sister reunite.

In a comment on the post, Christa said that she had "never seen Poseidon act like this with another dog at the dog park."

"He not only likes her, but I really think he knows her," she told Newsweek.

The viral video's comments section was full of users recounting their own stories of animal siblings being reunited after periods of time, as others urged the pet parents to stay in contact!

"I never thought about how a litter is actually just a bunch of twins," laughed one commenter, while another said, "You can tell they recognized each other by how comfortablethey look with each other!"

"They’re written in the same font," joked a third.

In the future, Christa wants to meet the pair in the park more often so that Poseidon and Abbie can play together and become part of each other's lives – and they've already hung out since, as some subsequent vids show!