I'm no IT expert, but I had a look at the database of names just last week to refresh my memory before meeting with the committee. The database was provided to the National Assembly. I'm not certain whether the names are from the phone book or other such source. I could get back to the committee with more information on that.
The software scans the names on the petition and flags those that are not in the database. It allows us to view only those names that might be problematic. Usually, they aren't, so the person responsible simply unflags them. In short, the software pulls up too many names, as opposed to not enough.