duplicates Evaluating $\sum^{n-1}_{j=0} \binom{n}{j}\binom{n}{j+1}$ and Find a simple formula for $\binom{n}{0}\binom{n}{1}+\binom{n}{1}\binom{n}{2}+...+\binom{n}{n-1}\binom{n}{n‌​}$. Close as a duplicate? Which is better duplicate target? Might they be even merged?

Personally merging seems to me like a good solution. (But I have misjudged possible candidates for merging in the past.)

If we should only close as a duplicate, I would choose the older one to remain open, since I do not see much difference between the quality of answers.

The only reason I see for choosing the other direction is that the newer question provides a bit more context. (So some users might be tempted to close the older one for lack of context. Back at the time when the question was posted, the site was much less strict on this aspect of posts.)

@DanielFischer Bummer I was almost finished with typing a comment along the lines: "This should be question, not answer ... links to asking good question and info about writing math... To help you get started I have edited the formula in your post to show you how to typeset something like that."

I assume that right thing to do after it was deleted is to rollback the answer back to original state so that it is not that distracting for other users. (At least the ones who see deleted content.)

After all, it was from unregistered account, so I guess that even if the finished writing my comment it would not make much difference.

@MartinSleziak Probably not. Sorry about the bad timing, I know how annoying it is when a post is deleted while one types a comment.

Well, it does not matter that much.

My question was mainly directed whether I did the right action by rolling back my edit.

Since I edited the post mainly in order to show the OP how to write math, and it is now rather unlikely that they are going to see the post, anyway.

At least this shows that some of the review queues are rather fast - this can be counted as a positive thing.

Yes, that's fine. I don't think it would have mattered much if you hadn't rolled back, but avoiding the extra load time for the image for 10k users is nice.

Close vote review queue is growing again.

I remember some users asking about the reasons for the larger number of items to review. The only guess I was able to suggest was this:

If there are a lot of duplicates in the queue, then that will probably be responsible for at least a part of it.

@DanielFischer If I may disturb you once again, one small inquiry related to our discussion about merging.

I guess I have misjudged some of the suggestions for merging questions. (The flags were still marked helpful. But the post were not merged, usually I found on my flag even a comment from a moderator why they decided not to merge.)

So if I occasionally flag for merging, but it turns out that merging was not the right way to go, it is not much of a problem, is it?

Well, I guess if it was a problem, the flags wouldn't have been marked helpful. But since you're already here in chat and we discussed merging before, I have decided to ask.

@MartinSleziak Not at all. Also note that it is always possible that if a different moderator handled the flag they'd have decided to merge. With few exceptions, it's always a decision that can go either way. Some moderators are more reluctant to merge than others.

Thanks for the response!