This actually happened to us, I’m serious!
We have had a grey cat, Gary, since 2017. She is/was the comfort cat for my wife while she was battling cancer. We got her from the pound. The cat, not my wife. Anyway…
In the summer we let our cats out during the day. We had five at that time, and not all get along so some go out the front door, some out the back. Periodically during the day we top up their food dishes, and we were noticing that no matter where we were, Gary was always there. It was uncanny that she was covering so much ground so quickly. Then one day I let a few cats including Gary out one door, then immediately went to let the others out the other door. When I opened the door there was Gary. It was impossible for her to get around our large house that quickly. I went and looked out the first door, and there was Gary. Turns out that Gary had a doppelgänger. To say that this cat was a twin would be an understatement, they were completely identical in every way, including mannerisms. This cat hung around all summer, and we fed her for a few months. As winter approached we became concerned because that’s when the foxes come into town to hunt nice fat cats. We advertised on the local Facebook pages for a few weeks to see if there was an owner but nobody came forward. So ultimately we adopted her out to a nice young couple. To this day we still aren’t entirely convinced that we kept the right cat, they were that identical.