That's exactly correct. It depends on how the database is set up, some question bank providers add everything they can find, on the basis, presumably, that extra questions can't hurt. Others try and trim them down to represent the CQB as closely as possible. As the various CQBs have been issued questions have been both added and removed, and the ones that were taken out were generally taken out for a reason, perhaps they were defective or didn't match the Learning Objectives. My philosophy would be to take out questions that I didn't think were in the exam but I can see why some databases would keep them in.