The double slit experiment has been replicated even with fairly hefty molecules.

https://www.nature.com/articles/s41567-019-0663-9

> Here, we report interference of a molecular library of functionalized oligoporphyrins with masses beyond 25,000 Da and consisting of up to 2,000 atoms, by far the heaviest objects shown to exhibit matter-wave interference to date.

It would be awkward to say that the 2000 atom molecule comes out of both sides... but it does, until you look.

The double slit experiment is not a duplication cheat of reality... it's weirder than that.