I think you'll find that the term 'bob' appears somewhere. It will probably be in the audio id tag. Some people give their files (& for audio id tags) xtra details to try to attract attention to them so they show up in as many searches as possible. Adding info to movies is also possible (outside of the actual file name.)

So much info can be added to an id tag (depending on the version of tagging) that a particular file may show up under a dozen or more artists.

eg: Pink Floyd/LedZeppelin/KingCrimson/...
Hold your cursor over one of these files that show up in more than one search. The id tag info will display. You'll probably find the person has deliberately put many other artist names in there as well. I seen some mp3's with at least a dozen or more artist names. Annoying ...yes!

But don't forget you can filter your results after the search by clicking onto the artist or album, etc. Particularly for a General type search.