I wasn't able to view your first link, but I think I know why this happens even though it should not happen. I think that what happens is that a user posts a question and that question gets many views especially when new and unanswered. Once the question gets answered the question is viewed less and you may not get another answer, so let's say you didn't get the answer you wanted and you may have a time frame as well. The question is posted again for a better answer or because no one answered and the user feels like by structuring the question differently they may get a better response.
I believe that the root cause of both of these scenarios is not understanding the true function of this site. I have to painfully admit that I was guilty of this when I first joined this site. I was in a position where I was hired as an admin but told to be a developer. They told me I would get training and I never did. All of my first tasks included code. I was using as many online resources as possible but with having only an admin background this was difficult. I would come up with code but there were always errors and the company wanted everything done yesterday. I would go on this site and post my code with what I'd tried and then I would wait. Sometimes I received responses immediately, but it wasn't what I needed. I had little time left so I would restructure the question and ask again. After being on the site a while I realized I was using the site wrong. I was using the site almost as if the site was a coworker I could reach out to fill my gaps in training instead of using this site to get assistance with a skill set I already had. I wanted them to finish work I had NO UNDERSTANDING of, but the site should be used when you already understand the concepts behind what you are trying to do but may have missed a detail or two, because then the answer will make sense to the user instead of it just being something they want to copy and paste into the system.
The best way to deal with this issue is what I think users are already doing which is flagging it as a duplicate. A lot of times users will add a comment with the name of the duplicate to let the person who asked the question know that there is already a question just like the one posted.