Are you sure about that? Of the 200 or so I've got records on there do not appear to be any instances of an upright, cabaret, or cocktail having the same serial number. There are instances where, for example, the Upright will be 01055 and the cabaret will be 01056. No overlaps that I can find though.
Also, the early cocktails appear to be the only ones with that particular serial number nomenclature "00385". The early uprights either started "10xxx" or "01xxx". All the cabarets I have data on start "01xxx".
Of the 20 or so cocktails I have data on, only one other would appear to start with a "00". The others appear to follow the same types of serial numbers that the upright DKs have.