1950s. Doppelganger monsters in human disguise are trying to enter the building. They all mimic the looks of Francis Mosses, milkman from the 3rd floor. Their goal is to convince user to let them in. All Francises are fake.
Doppelgangers come every now and then, sometimes several at a time.Some have wrong ID, others have multiple eyeballs, noses or mouths, weird voice, are bloodied, disfigured etc. They all have different personalities.
This situation continues indefinitely and is comedy horror.