Is it right to downvote questions only because they are a duplicate of another question? Shouldn't voting be based only on the relevance of the question?
A down vote on the main site means this:
So if a duplicate is displayed when a user is typing in their question title, or pops up while they're typing out the body of the question and they haven't checked if it is the same as their question, then some might argue that is a lack of research.
Down voting on meta is different and normally shows some sort of disagreement with the question at hand.
That said, if a meta question shows no research then it'll likely get down voted.