Cant help you with getting from Apple Address Book to FMP (I'm on PC) but it sounds like you want to do two imports and a purge.
Import1: Import the whole address book with name and Home email
Import2: Import the whole address book with name and work email
Do a find for the equal sign in the email field (this finds blanks)
Delete the found set.
Note 1: This presumes this is a one time event (but is quick enough that I'd use it once a month if needed rather than automate it)
Note 2: It seems an odd way to store the records. Why store everyone twice? Why not have two email fields? And if not two fields, why not use a related email table? If Suzie Smith gets married and is now Suzie Neidzelak, will you remember to change both records? Why not just have one per person???