Abstract: A key retaining multiple lock mechanism, suitable for parcel lockers and other structures and capable of being mounted on doors for such structures, has a first lock with a first key trapping tumbler mechanism. The first lock has a strike-engaging tongue and a spring loaded bolt cooperating with a second lock dead bolt structure. The dead bolt is operated by a second key to extend and retract the dead bolt. When extended, the dead bolt compresses the spring-loaded bolt when the mechanism is in a locked condition and acts as a stop when the mechanism is in the unlocked condition, preventing relocking of the structure without first retracting the dead bolt with the second key.