we have different projects that have their own address books. The project manager creates newsletters based on the project's address book. Sometimes, the newsletters are the same for two projects, lets call it project A and B. So the manager of project A sends the letter to his contacts. A few days later, the manager of project B wants to send a letter to his contacts.

The problem is, some contacts in the address book of project B are also in project A. These contacts would get the same newsletter twice.

Is there a way to compare two address books and single out the double entries? I don't want to have a third address book with all records from A and B together. I need address book B without the records of address book A.