Is explaining why a question is not a duplicate a valid reason to edit the question?

Question

When a question has been incorrectly marked as a duplicate of another question, is editing that question with a note explaining why it is not a duplicate a valid reason to edit a question. Recently I suggested an edit to a question in such a manner and it was rejected.

It was clear from the comments and title and the question itself that only a small aspect of the question was addressed in another question, but the main question was indeed original. A user reading a question that has a duplicate flag at the top will be misled.

Is putting a note below that tag explaining why it is wrong, a valid next step after making a comment, or should one go immediately to that site's meta go get support from the community? Or should the question be flagged. What is the proper protocol for dealing with non duplicates that have been marked as a duplicate -- if you are not question's author?

For example, a question on SO, which asks mostly about adding a variable value to a plot in R, is being marked as a duplicate of adding an 'expression' to a plot (just because expression is mentioned in the title). At no point in the proposed thread is variable values even mentioned. The OP posted a comment clearly explaining the difference and yet editors continued to mark it as a duplicate, without even responding.

So my good faith solution was to suggest an edit to the question with a note explaining why it wasn't a duplicate, which was strangely rejected for "changing the meaning of the question", despite the meaning clearly not being changed at all (All I did was add "There is an answer to question X: it does not address this question because of Y", where Y is both in the OP's title and in the body and explained by the OP in a comment).

So my question is, are edits explaining duplicates reasonable edits if they are not done by the OP?

Answer 1

Yes, this is a valid reason for editing a question, especially as it may result in the question being reopened.

But if you do not have full edit privileges then doing it as an edit suggestion may not be the wisest thing to do, there is no guarantee that the suggestion will be accepted.

You haven't linked to the (failed) review, so I can't comment on what you wrote. But I would advise to keep the edit concise and to the point, make sure you include a reasonable edit comment for the reviewers, and make sure you fix any other issues in the question.

Edit:

After viewing the review that's been edited in, I would say that you weren't quite as clear as you could have been, hence the rejection. Don't blame the reviewers - it's good that they're setting the bar high. Just think of it as one of those things that can happen, suck it up and move on. Jamal mentions that:

Editing in such info is wrong as it's not part of the actual question but a direct response to a comment or answer

to me that's a little confusing. In this case there was no reason why the OP couldn't have edited his own question to show it wasn't a dupe, then it would have been forwarded to the Reopen review queue. But having said that, it has been longstanding advice on Meta.SO that you should mention in your question why it it isn't a duplicate. Your main fault was not being quite as clear as you could have been, and doing that as a suggestion - which was seen as changing the intent of the question.

Answer 2

I too would agree with those rejections. Editing in such info is wrong as it's not part of the actual question but a direct response to a comment or answer. This is discouraged in general.

In many cases, neither of the closers would have already provided a comment (excluding the "possible duplicate of..." one), so you wouldn't be able to respond to them. Instead, you would have to post on the respective site's Meta and explain your reasoning. This could also allow for new reviewers to determine whether or not the question should be reopened.