Because of this the policy now is that some duplication is good[1]. Though a lot of users are still rabid about closing, I always try to answer inexact duplicates, and if the their title doesn't lead to duplicates, point out the things they should have searched for (ie, object picking, hit testing and point in path are three names for very similar things)

[1] http://blog.stackoverflow.com/2010/11/dr-strangedupe-or-how-...