Can you provide some examples of duplicates where the "duplicate" is actually something entirely different? Maybe I can help improve the situation.
IIRC this happened while other users seemed to be happily karma farming best-of questions.
I haven't seen so many lately but I've decided to start making bookmarks on them and here is one I found a few days ago: https://stackoverflow.com/questions/13202705/what-are-the-us...
Myself I've witnessed first hand a question about networking being shot down on networking because it was between company networks instead of inside company networks.