The Turkish Multiverse is a bizarre one, in the fact that the histories of the universes it contains are incredibly similar to the histories of entire multiverses, and yet, are different enough to not be considered parts of those separate multiverses.
For example, take Turkish Spider-Man. The "Prime" Spider-Man is a heroic, super-strong superhero in the city of New York, risking life and limb to keep people safe from evil. Turkish Spider-Man, on the other hand, is gang leader and counterfeiter, murdering people for kicks. Their costumes are similar, but little else.
As another point, these "Derivative Universes" are located closely enough to each other that they qualify as their own separate multiverse. It has been posited, that, due to their proximity to each other, that there is something inherent of the nature of these universes, that somehow, when in contact with other multiverses, that they somehow copied various contents of the multiverses that they encountered. It has also been suggested, that these "Derivative Universes" were actually portions of the Multiverses they bear superficial resemblance to, and something drew them all together.
Both are interesting theories, but so far, the true nature of the Turkish Multiverse remains unsolved.