Question: If I had two divs, both with id="myDiv", would `$("#myDiv").fadeOut();` fade both divs out? Or would it fade only the first/second? Or none at all?

How do I change which one it fades out?

**Note:** I know duplicate id's is against standards but I'm using the fancybox modal popup and it duplicates specified content on your page for the content of the popup. If anyone knows a way around this (maybe I'm using fancybox wrong) please let me know.

Answer: 
"Note: I know duplicate id's is against standards"

Then don't do it. You have already figured out two problems. It violates standards, and it interferes with jQuery's (and indeed the regular DOM's) selection mechanism. There will probably be more issues in the future.

Quite possibly, you *are* using fancybox wrong, in which case I hope someone familiar with it helps you. Or worse, if the script itself is flawed, you shouldn't use it.
Since $('#myDiv') will only return the first div with that ID, you'll have to find all elements with that ID using this trick:

```
$('[id=myDiv]');

```

So, for your case, to apply the fadeOut to all of those divs:

```
$('[id=myDiv]').fadeOut();

```

And if you want to make sure your page doesn't have this ID twice then you can remove the extra ones by doing this:

```
$('[id=myDiv]:gt(0)').remove();

```