Q:

Is it a bad thing to have your question marked as a duplicate? 

This morning I had my question closed and, upon browsing through the answers to the proposed duplicate, I did find half of an answer to my question. 
This leads me to wonder about some things:

Is it frowned upon within the ELU community to ask a question that is similar to a previous one? 
Is there anything wrong with asking a question that has been asked before in the hope of better quality answers or answers from different viewpoints? 
Should I, as an enthusiastic user, feel dejected or guilty? 
Are there any negative effects from having a question closed as a duplicate?  Does it affect your respect in the community? 
Why are questions allowed to be marked as a duplicate immediately?  Should there not be a grace period in which there's a chance for new, more informative answers than those of the "duplicate"? 

Please note that my points are nothing more than small concerns; I do not object to the closure of my question. 
The main reason I am asking this is because as a frequent user of the site, I feel that I should be as familiar with it as possible. 
I thoroughly enjoy answering and editing questions asked on ELU and I have even gotten many helpful answers myself. 

A:

Answering your questions in no particular order...
In general, duplicate questions are not desirable because you end up with answers to the same actual question spread out across multiple question posts.   When the next person comes along with that same question, it's much harder to find the answers.   That's why duplicate questions are closed before they can accumulate more answers.   
If you are unsatisfied with existing answers to a question, there are several ways to draw attention to an old question, but asking the exact question again would only result in the new one being closed as a duplicate. 
If your question has some subtle but important difference from the existing one, it's OK to post a new question.   But it would be advisable to call out the older one in your question to preemptively stave off people closing yours as a duplicate. " This may seem like a duplicate of (this other question) but it's not, because..."
It is natural to feel dejected when you receive negative feedback, but it's just a part of life on the site.   It is very easy to ask a duplicate question accidentally.   As long as you did your diligence in searching for an answer and reviewing the list of 'potentially similar questions' on the ask screen, you shouldn't feel bad. 
As Mitch already answered, closed questions don't really count against you unless it's a repetitive problem.