When another door key unlocks your home

Another Door Key	found by		Someone else	who alters the Key	and Enters Your Home

You live in apartment #15. Your landlord, in an effort to be efficient has purchased a set of 20 keys. A contractor who works at the apartment complex finds a key to the apartment next door, #14. Armed with the key / door relationship knowledge, the contractor is not only able to make a key for your apartment, but for all 20 apartments.

Does this sound unbelievable? Read on ...