Ironically, I'll bet this question is a duplicate of other questions regarding duplicates, but I see little harm in sparking some new conversation here, even if we tread over old ground that many others may not have seen.
In any case, the question I want to pose is this: When is a duplicate really a duplicate? I ask this because I answered this question in some considerable detail, only to see it marked as a duplicate of this question. Upon inspection of the duplicate charge, I saw that the so-called duplicate question was not so: the integrals discussed in each question were related tangentially by an integration by parts. (Actually, the original alleged duplicate question involved a sum and not an integral, but never mind.)
Luckily for me, I happen to hold gold badges in the tags of the question I answered, so that I was able to exercise the power to unilaterally reopen the question. But that is neither here nor there. What I want to know is, what on earth is a duplicate?
Is it a question that asks a duplicate, i.e., exactly the same question as another?
Is it a question that may not be a true duplicate of another question, but produces the same answers?
Is it a question that that may not even generate the same answers, but poses essentially the same challenge?
Or is it something else?
I'd like to hear from others, because I am under the impression that a duplicate is an exact copy, and those who answer such questions may be asked to migrate their answers, if unique, to the original question. (I have done this in the past. I will not do this in the case cited here because it would be ridiculous.)