I recently set up a new library section for Mystery Science Theatre 3000 versions of films. I'm slightly ashamed to admit that I also have the original versions of some of those films in my main movie library (there's no accounting for taste) and when I search for a film I get 2 identical results, one from each library.
So then I have to either play each one, or dig into the info to find which version it is. If the plex web interface and other clients would display the library along with the search result it would be very useful.
Or, for bonus points, correlate all the results with the same metadata into a "stack" and when I go to play it, offer me a choice of which one to play. But just showing the library name would probably be easier!