Not sure if this fits but The Clearing has two timelines that run at different speeds. A great film.
I am quite surprised that the first two that came to my mind, Lost and Eureka, weren’t mentioned until the 32nd and 37th post. I figured they’d be of the first mentioned.
Why would we? It only has one timeline. There’s plenty of time travel, but near as we can tell, it was all “supposed” to happen. Nothing that happened in the past ever changed the present/future.
The TV show Seven Days. First we would see the “real” timeline then Frank would take the sphere and change the timeline.
Spoilers for Lost’s last season (not sure this is really necessary but…)
Even though it was purgatory or heaven or limbo or something the Flash Sideways from the last season fit the premise of this thread. They were a reality where the Island sank into the sea long ago.