Sometimes when a question is marked as a duplicate it has already 'developed' into an interesting Q&A link.
An example is Could dark matter be wrong? on the Astronomy website which is marked as duplicate of Are there any alternative explanations for the gravitational force we attribute to dark matter?. (I am using this as an example because it triggered me to write this question/request, but there are many other examples).
Now, the 'problem' that I see, is that the question that is marked as duplicate links to that particular duplicate question, but the other way around does not occur.
This is problematic in such cases where the marked question is actually having useful and interesting (possibly better than the original) answers.
My suggestion is that we should also link back from the question that is the duplicate question, to the question that has been marked as duplicate.