When I see this happen I try to educate the person on how to use a search engine properly. Searching may seem like an obvious thing but for someone who has not yet learned how to formulate keywords properly it can be a complete mystery. When doing this I prefer to focus on the keywords that I would use to find the relevant information instead of focusing entirely on the task at hand. It's sort of like that old adage, "Give a man a fish and you feed him for a day; teach a man to fish and you feed him for a lifetime".
Now for people who are just being lazy and expect others to do their work for them; I think this is a non-issue. They won't be around for long because they will quit this like they quit everything. You'd get really stressed trying to deal with this on a daily basis. Maybe it's best to just deal with this like it's noise and ignore it. A system that can deal with this 'noise' will bury the page quickly so it disappears silently into the background based on some usefullness rating.
In any case it's best to be as helpful and courteous as possible since many of the people which this topic deals with are very young and have had no proper guidance in these matters.
Also, when it comes to redundant questions it helps to realize that most websites have very poor internal search engines, it can take a while for people to realize that StackExchange actually does work well in this area.
Perhaps the redundant question notices could have a short tutorial on how to use this feature. The way it's formatted now seems more like a "Go away, you did something wrong" notice. Because it's not instructive it does little to prevent this from happening again.
Maybe some programmer can find a way to easily merge the pages which are redundant.