I was dealing with the exact same problem. My rather large library suddenly had 3 entries for each item except only one of the entries had a filename associated with it. More on this in this thread.....
http://yabb.jriver.com/interact/index.php?topic=83348.0The only two things I can think of that might have caused this are :
1. It only happened after I backedup the library and then put a brand new system in place and restored the library to the new system. It worked fine and everything was good but a couple of weeks later, the multiple library entries started up.
2. I have all my files on a server that has been a tad flakey. It goes blue screen and restarts every few days for some reason I haven't been able to figure out. It just reboots itselft and the MC19 client works fine.
Perhaps these dead library entries are happening if the network source files suddenly aren't there when auto-import kicks in?
(eg: during one of my server reboots)
Auto-import couldn't fix the problem even when I set the fix broken links to Yes.
I eventually just manually deleted the entries without filenames and that seems to be stable now after a week.