Island Mimic
My mother used to tell me this story throughout my childhood as we all grew up. It occasionally came up during scary story time.
It gave me uncanny valley vibes, as I wasn't aware of the simulation theory, the matrix or glitches. But this story does sound like a real life glitch, but I am more convinced that whatever happened was sinister, and involved Jinn (I'm Muslim, and the existence of Jinn is a part of every Muslim's belief)
The story: We are from an Island nation, and back in the 70s right when the country was just starting to catch up with the rest of the world, most of the developments happened in the capital city, while the islands lagged behind.
My mother's family belonged to one of those islands and lived her childhood there before coming to the capital and meeting my dad and getting married.
Her dad (my grandfather) used to carry a small rowing boat and go to the nearby uninhabited islands everyday to collect fallen coconuts, gather firewood and timber etc and come back to his island by the time the sun sets. That was how he earned his money, and like clockwork, did it everyday.
Until one day.. well, mom explained it like this; my grandfather had gathered up piles of tied up firewood bundles and loaded them into the tiny boat that was tied up on the shore. There were two bundles left, and the sun was already set, so he hastily grabbed one bundle and loaded it into his boat and turned around for the other - and he saw exactly him, picking up the last firewood bundle, putting it up on "it's" shoulders and walking towards my grandpa's boat. My grandpa saw an exact copy of him, mimicking his movements just like how he did and walk towards the boat that my grandpa was now untying to get the hell out of that place.
My mother told me that according to grandpa, he didn't care about that last bundle of firewood and got into the boat and sailed away from that island as quickly as he could, and after several minutes when the island was hundreds of meters away from him, he turned around to see "himself" still on the beach with the bundle of firewood on his shoulders, looking right at my grandpa.