Thanks for telling me, I'm embarrassed that I didn't know that about the green search bar!!!
Any idea why it could be displaying the wrong number then? I know it sounds like a tiny nitpicky problem, but I do have a good reason for wanting the correct number.
Note: on earlier versions of Calibre, the number of extras changes. It's 5 extra books on the latest version, but the difference has been as low as 3 extra books and as high as 10 on other versions. When it was saying 10 extra, I did find that some duplicate books had been created somehow, but that only happened once, and I've never found duplicates again.
Thanks for developing Calibre, by the way, it's awesome either way!