This question gives space to another scenario the currently accepted answer isn't considering.
What if my question was marked as duplicate and I disagree with it?
In this specific case, I suggest you to write a comment or edit the question explaining what is different from your question and the other one and then vote to reopen.
As a reviewer of Reopen ...
Your question is marked as duplicate, but this might not be the reason why you are getting a down-vote.
As pointed out in the comment, you have a net gain of reputation point, so in terms of reputation points, you are not being punished.
Yes you cannot delete your post, not because it is marked as duplicate. You cannot do that since there are upvoted ...