Master/Skeleton Key in the olden days this is what was now called Keyed Alike which in turn means 1 key to do several Locks.. These days we now can do a Master Key System, this is done for Businesses so that they can control who has access to different areas and all keys are stamped with an issue number on them. Master Key systems then allow the owner of the system to allocate staff a key to there level of access and sign for the issue number so they have the reassurance that no keys have been cut.