If you are seeing there are dulpicates in these questions, by all mean pare them down. Select one, in your opinion, which answers the question and put the other ones as duplicates. The process of closing a question involves several people to review the action, so it shouldn't be an issue. Only kids have the ability to throw the close hammer at it and make it stick on the first go around.
If the questions are different (different circumstances, but same outcome), it is my opinion these should be left open. To me this could help others who have a similar question get to the end result and hopefully not ask a question which will get closed.
If, on the other hand, you are suggesting we should just point these question towards the main question through a comment or something to that effect, I don't think there is any issue there, either.
One of the issues which happens on the site is people with no mechanical understanding ask questions. Because they have no typical understanding, they aren't asking with the right terms and therefore the other questions don't pop up to them as a possible answer. This is just one of those things we have to deal with.