Abstract: By providing a lock such as a padlock or deadbolt lock wherein the components forming two wafer or pin cylinder assemblies, interconnected so that one key and wafer cylinder locks and unlocks the shackle or deadbolt and the other key and wafer cylinder when key actuated blocks and unblocks access to the first key cylinder's key insertion hole therefore double locking the overall mechanism, resulting in increased security, creating multi-levels of security and various additional methods of security which is attained through standard key and cylinder key bit configurations.