On a number of occasions, I have seen questions closed as duplicates although the linked question either did not have answers, or had only poor answers, and in some cases it had already been closed (often for quite different reasons). In such cases, I think that to close a question on the grounds that it is a duplicate of a question which already has answers is inappropriate. I think that to close a question on this ground, it must not only be a duplicate but also the answers given must genuinely answer the current question.
I have just voted to leave open the question Why do higher harmonics have a lower amplitude than fundamental frequency. It had been linked to the closed question Is the first harmonic the prevalent frequency? [closed] (which does have a single, very good, answer as it happens). It was closed, probably correctly, because the question lacked clarity. Consequently it is not visible to many users.
The suggested duplicate question has 1 upvote, and the answer has 5 upvotes. The new question, which is much better phrased, has 21 upvotes and the accepted answer has 36 upvotes. A total of 47 upvotes have been given to the other 5 answers. And yet, there were already two votes to close.
Surely we should not be voting to close high quality questions and answers in favour of questions which have already been closed? Can I ask that we do not close questions as duplicates unless they are genuinely duplicates, and unless the answers given completely answer the current question?
Also, should we not look at the way the system works? It does not seem reasonable to me to close a question because it duplicates a question which is already closed and is consequently not visible. It is entirely reasonable to ask whether an answer to a closed question answers the current question. But it is not reasonable to close a question simply because a similar question has previously been asked.