Time itself is probably synchronous between the worlds, but because they split into alternate realities a long, long time ago there is undoubtedly some divergence in culture and people. Darklander doesn't seem to recognize Minfilia, for instance. As our stand-in during trailers and cinematics, Derplander is highly likely to be very familiar with her. So there is no Minfilia analogue on the First Reflection.

The only question then is why they have the same naming schemes as our cultures, but asking such questions is not wont to provide answers. Probably not best to dwell on it.