Earlier today, I was pointed towards a bunch of question that were duplicated one of the other. But while reviewing the stuff linked to the question I noticed that most of those questions don't have the enough elements to qualify as exact duplicate of the question they were linked to. This is rather preoccupating since duplicates are the hardest to review/evaluate:
If it's a duplicate we need to read both the questions - the one we are closing and the one we are targeting - to ensure that we select a proper duplicate target.
Most of our queue is (was?) composed of duplicates, it makes harder for reviewers to evaluate the questions as duplicates as the question they are reviewing is too bad/unclear to make the reviewer feel sure what is being done., and then either: do not review or robo-review and just agree with the previous.
How to solve? If there is a possibility that the questions is already asked or you found something similar, but the question is unclearbut the question is unclear, flag/vote as unclear, and leave a comment of a possibly related question. This will help reviewers greatly and in the meantime can help OP to say "Yes" that was what I was asking or "No" and clarify the question.
Remember, the duplicates should have the same or more quality that the question they are being linked to.