When a question is closed as a duplicate, the ideal result is presumably that the questioner, potential answerers and future visitors will head off to the linked question and that any new answers will be posted there. But how practical that is in reality depends on how close a duplicate it actually is and on the quality of the original and its answers.
I think it would be useful for the linked question to include some message along these lines:
Several questions have been marked as duplicates of this one, meaning that anyone viewing them is directed here for the answer. Please help by ensuring this question has high quality answers. If you answer one of the duplicates here, please be sure to include any additional information from the duplicate in your answer.
The bold text would be a link to a list of the duplicates.
I think this would
- encourage people to edit the question and answers into a suitable form for linking to
- help answerers to easily find the duplicate questions if they need to
- encourage answerers to check that their answers will also help people who arrived via a duplicate question.
- in some cases, indicate the need to keep and improve the question rather than delete it
- make it easier to find and tidy up groups of duplicates
- make it easier to identify unsuitable "duplicate targets" so as to choose better ones.