Thanks to this home video that has gone viral after being uploaded to YouTube on 27 May, we have an idea of what it's like.
Sileika wrote the following caption on YouTube: "My 10 month old son just met my wife's twin for the first time. His reaction is hilarious :D"
In the video, the boy's mother holds him as her twin walks through the door.
The baby goes completely wide-eyed staring at her and soon puts his arms out for a hug.
Does he assume it's his mum, again? Probably.
He stays in his auntie's arms while his mum says: "Who's that? That's your aunt Steph!"
To test out who it is, the baby begins touching his aunt's face and smiling at her. Although he's happy to sit in her arms, he does still look pretty shocked.
We don't blame him, it must be a seriously confusing experience.