A while ago I noticed a question was a duplicate and so marked it as one using the flagging option. The other question had recently received an answer and I am pretty sure I up voted it, but I may have been the only up voter. The questions are asked in a very similar way so I think any one looking for that question and came across one would also come across the other. The "duplicate" is not showing up as a duplicate. Now there are two answers to the question I did not flag, one of them with 9 up votes and was also accepted.
What should be done? Should I leave it since it seems the community did not agree that it was a duplicate? Should I flag it for moderators attention? Should I come to meta and tell people to close a question as duplicate? Should I gain 1700 points and maybe have the powers to close it?
What is the most likely reason the question I marked as duplicate was not determined to be a duplicate?