Joy is working with the city attorney to find parcels that are associated with more than one unit.
EAS contains a reasonably good, if not perfect, data set for answering this kind of question because it's used to support building permitting.
In any event, here is the CSV file with that contain these data.
If you view these data with excel, consider setting a custom format for the blk_lot column so you can see the leading zeros!
The SQL query to support this is here.