Question: I recently flagged a post on SO as "Unclear what you're asking". Afterwards, for whatever reason, I clicked `flag` again and found this:

![enter image description here](https://i.stack.imgur.com/lh7kM.jpg)

Is there any reason it says I've raised a duplicate flag too when I'm positive I have not? Is this a bug? The question, as of 2:56 PM UTC, 11 September, 2013, has only existed for 26 minutes and the flag doesn't exist in my flag history:

![enter image description here](https://i.stack.imgur.com/Lm2re.jpg)

**Note**: There are several similar questions:

* ["You have already raised this flag" Well, not really](https://meta.stackexchange.com/questions/188818/you-have-already-raised-this-flag-well-not-really)
* [No, I haven't already raised this flag (not here, anyway)](https://meta.stackexchange.com/questions/189288/no-i-havent-already-raised-this-flag-not-here-anyway)

The first was never answered and the second is unrelated as it appears the person asking did, in fact, raise the flag they assumed they hadn't raised.

Answer: 
The [answer](https://stackoverflow.com/a/18673478/1488917) should not have been deleted.

The answer is not a good answer, but nonetheless attempts to provide inputs and suggestions as to what the problem may have been. It should have been downvoted at most, but not deleted.

Chances are that the first line in your answer prompted the deletion:

> 
> Maybe you should post some code?
> 
> 
> 

This should not be a part of answers, but added as comments to the question.
It seems like a reasonable, though not stellar answer. Three people thought it was good enough to upvote, and it seems to contain useful information. 

I don't think it should have been deleted. 

Here's the full text of the answer:

> 
> Maybe you should post some code?
> 
> 
> Check the memory traversal if you use loops. You should traverse your
>  buffer in the right order, otherwise you may have cache miss at each
>  iteration. If you use nested loops sometimes you only have to switch
>  the x/y iteration order.
> 
> 
> Also, don't read data from graphic memory. It tends to be slow. Only
>  write to PBO.
> 
> 
> Edit:
> 
> 
> It looks like a syncro issue. I'm not sure you need to map pbo at
>  every frame. Check this [link on OpenGL Pixel Buffer Object (PBO)](http://www.songho.ca/opengl/gl_pbo.html).
>  There's also a workaround for stalls which could improve things
> 
> 
>