I am helping a friend who has a large amount of files with potential dupes, spread across several drives. I told her how to do it, she came back and said, nup, doesn't work. I said rubbish, works fine, and... doh, I couldn't make it work. Came here, searched, found this post, close enough.
Read it, read Jon's reply, and aha! Regardless of the status of the lock or other stuff, double clicking the "Add folder to search" allows you to add more than one search location, but long clicking to get the ... then navigating to a location, doesn't work. It seems to be wanting a file, rather than a location.
So this isn't a question on how to search multiple places, it is a question of is this a bug? I assume it is, because Jon's reply in the above post suggests that double clicking and long clicking (to get the ...) are the same, and they aren't. Well, at least as far as I can see.