Why prevent duplicate questions?

Question

I'm wondering why there is so much work to close duplicate questions.

We can see that the Stackexchange concept allows users from all around the world to find answers very efficiently.

Wouldn't it be better to have the maximum number of answers even for the same question as each one is slightly different. The more there are answers the more a user can find his one.

Are we limited in disk space or something ?

Imagine a question badly asked one day then the same well asked later that is easier to find from google, which one is supposed to be closed as duplicate ?

Answer 1

If the earlier question is answered nicely and in detail then it's better to close the current question. Because,

1. No point in giving extra efforts for whatever is answered already (reinvent wheel)
2. If someone desires to add more, than he/she can always add an answer to the original question; (though it may not get that much attention)
3. For the future viewers, there is a single point of query rather than going through multiple questions
4. To stop the SO users to copy-paste from the old answers and gaining unworthy reputation

Now discussing the other aspect:
The duplicate question is closed but not deleted because,

1. It may happen that question may not be exact duplicate, but related; so in such cases it can be reopened
2. If earlier question din't get any attention then present question can be reopened for having more attention
3. A single question may be asked in different ways; if someone is searching some query on google then the most matching question may appear at the top. But still Ultimately all duplicates will point to single original

Answer 2

When the question is "I have this problem" and there is already an accepted answer that solves that problem, duplicate questions can make it more difficult to find that correct answer. When used that way, the duplicate feature makes the site more helpful to everyone.

But in my opinion, the duplicate feature is widely over-used. Questions are marked as duplicates even when they could contribute meaningful information to a site. We really don't need to worry about disk space, so there's no reason to reject a question that could possibly make a site more helpful.

Here are two situations I can think of where using the duplicate feature might not be appropriate:

When the existing question is wider in scope than the new question.

Question A asks about X, Y, and Z, and gets an accepted answer. Question B asks about Y. Question B can technically be marked as a duplicate of Question A because the answer contains the answer for Question B. But there is obvious value to Question B getting its own answer. The next time someone is curious about only Y, they won't have to read through X and Z to find it.

When the existing question doesn't have an accepted answer.

The point of every question is to generate an accepted answer. If the existing question doesn't have an accepted answer, there's no reason to think that it's better than the new version of the question. We should be glad that people are willing to post the question in a new way, because it might draw attention to the question and generate a correct answer.