I have noticed several instances where a question has been closed as a duplicate of another question when the two questions have the same answer, but aren't really the same question. A recent example is how to fix “object has no uniform scale”?, the question marked as its duplicate is Why is it important to apply transformation. The new question is asking about what the message means and how to get rid of it, the old one is asking why you should apply transformations, the questions are really different but they have essentially the same answer. I have seen several other instances of this as well.
Personally I think we should only close duplicates if the question is the same. The purpose of duplicates is to make sure people search the site before they ask a question. But, using the example of the question I mentioned above, the asker (especially if they are a new user) definitely could not have even found the question that was marked as a duplicate, let alone tell that its answer was the solution to his own problem since he had no idea wheat applying scale means.