Following from this topic, I'd like to posit a few hypotheticals about duplicate questions, and ask what we should do in each case:
Hypothetical #1: The situation described in the title. A question is a duplicate, but for one reason or another, it's clearly better than its antecedent question. What do we do? Is this cause for "disciplined deletion," or is there another solution?
Hypothetical #2 (This comes up very often, so let's call it not-so-hypothetical): A question is asked that duplicates an earlier question, but with a different focus. For example, it focuses on a subcategory of the original question, or draws attention to a particular detail or example rather than the general case. A great example of what I mean is this question, which was closed for being a duplicate of this question. Also consider the relationship between this or this question and this question; similarly this and this.
Hypothetical #3: Same as #2, except the new question brings an example that, while technically included in the scope of the old question, would never be considered if the new question did not specifically bring it. A good illustration of what I mean is this question with respect to this question.
Hypothetical #4: This is a trouble I've been having with a recent question of mine, so it's not so hypothetical up to a point.
I posted a duplicate. The original question was in fact asking the same thing as mine, but every responder misunderstood it and answered a similar, but slightly different question. (They answered about "translations" rather than "transliterations.") The question about transliterations remains unanswered.
When my question was identified as a duplicate, I got a message saying this: "This question has been asked before and already has an answer. If those answers do not fully address your question, please edit this question to explain how it is different or ask a new question." The trouble with that in my case was that neither of those two options could be used to get a better answer; nevertheless, I attempted to do the first.
I suspect that in fact the proper thing to do would be to set a bounty or otherwise try to attract attention (and correction) to the old question. But what if--hypothetically now-- that wasn't happening? What if an answer had already been approved to the original question--even if it didn't really address the important part--rendering the question far less likely to get new answers in the future? What would be the proper thing to do?
Thanks for your feedback.