As has been said in the comments, you have to be careful when doing what you suggest. Do it to many times and the system flags you and you get a question ban.
There is an issue on SO with duplicate questions. Once they get marked as a duplicate the amount of attention paid to them -even if you do edit them - drops off sharply .
Your preferred solution would be to edit and flag for Mod attention. However if this doesn't work then you have 2 options.
One: try and get whatever solution was posted to the 'dupe' question so that it fits your needs. Hard, but if it's close not impossible.
Two: Leave your question up, it's a duplicate yes but the system knows how to handle duplicates. Next, sit down and think about your question, think of any phraseology or approach that you could take to make your question clearer and less like the dupe.
Then when you write your new question include the research you did. Point out how much effort you have put into it. Use links and say things like:
"I found this question here and it was good, but ultimately my question is different in X way".
If people can see the effort put into it. Can see that you did the research and it's clear to them why it's not a duplicate then they are much more likely to help you.
Remember that all the work done here is on a volunteer basis. We like helping by answering questions, IF we feel like we are actually just answering the question; not doing work for someone for free.