I've noticed this happens a lot in short questions. The OP can think of nothing more to say and just copied the title into the body (or vice versa) and adds a short sentence that adds little to the question.
If we edit out the title in the body, there is usually nothing or little left. If we leave it, it is redundant and vague. If we rephrase it, we run the risk of altering the OP's original intent. If I see this happening, what should I do? Do we have an existing policy on this?
This is certainly a red flag, since very short questions tend to be bad questions. However, rather than editing the post in that case, simply flag it to be closed or downvote it.
However, some questions are legitimately short. Those you can leave alone. There's nothing inherently wrong with repeating the title in the body, so if the question is otherwise fine, there's no need to edit it.
The idea is somewhat like emails. Should the subject of an email be repeated in an email?
I don't think an exact copy should occur, that is stylistically annoying, but I do think there should be some repetition of the concept.
Very often a person will write something in the title, then in the contents go in a completely different direction. What results is that some answer the title questions, and some answer various things in the body that are unrelated to the title. And it is still unclear what the OP really wants, the title question or the slightly different question in the body.
Also, as to UI design, the title is often separated from the body to such an extent (in size/weight/kind) that it is hardly read at all after the link from the main screen is read, so there is the problem of a discrepancy in understanding of the title and the body even when consistent.
For example, in the question:
it was very unclear in reading the examples that the title had anything at all to do with the examples given, in fact it was easy to answer the problem in the example rather than trying to answer the title.
We should discourage repeating the body in the title. A title is not merely the first sentence of the body. It's something else altogether.
For example, the title of this question really should have been Repeating the Title in the Body do it the way people set the titles of books and movies in English (let’s call this titlecase), or else Repeating the title in the body if you capitalize the first word only (let’s call this sentence case), as some European publications do.
Sentence case works best with actual questions or long titles. Short titles in titlecase should look like
What you say about altering the OP's original intent doesn't apply to question's titles, as long as the title is pertinent with the question. For example, we are required to avoid writing some words in the question's titles; if you change the title to use c*nt, you are not altering the meaning of the question.
Changing the title to avoid it is equal to the question's text is a minor issue. In such cases, the more important issue is that the OP didn't probably put much effort in writing the question, and s/he didn't provide a context for the question, or give more information.
There are simple questions that don't need much, and for those questions it is probably fine if the question's text is equal to its title. Still, I would personally avoid doing that because it sounds like lack of effort from my part.
I usually edit it out.
If what remains is little, it was little with that part anyways, so why keep it? It's redundant and serves no purpose (besides being redundant).
It is certainly a red flag, like JSBangs says, because if you can't add enough context, then your question has some problems.
I think this is a matter of personal preference - specifically, the preference of the person asking the question. If you the reader don't like it, that's too bad.
I personally habitually copy the most pertinent block of words from an email and paste it into the title before I click on Send, so that's where I stand.
I used to think it would be a good idea if people were encouraged to change titles like "What's the difference between word1 and word2?" to a standardised "word1 vs word2", because I thought that would make my future searches easier. But I kinda lost interest when the debate ended up getting bogged down in whether it should be vs / vs. / v / v. / versus / whatever.
So long as the question is clearly presented, I say let the original words stand.
