[Solved] Duplicate styles in the style drop down

I've scoured pretty thoroughly, and haven't found an answer to this. I'm using CKEditor in a custom web app, and I'm using a custom conifg file to define styles, as well as a custom css file to actually style the contents of the editor, so that the user sees their styles (approximately) as they'll appear in the page they publish.

The problem is, my styles dropdown is displaying both the custom style name as defined in my .js file, as well as the CSS class name from the custom CSS file. I only want it to display the name from the .js file. 

So, using the "Highlight" style as an example, my styles dropdown has this: http://cl.ly/image/3b2W1J1L0E1q (good!)

and when you scroll down a bit...

this: http://cl.ly/image/2i460U0m3X0i (bad!)

My .js file declares it like this: http://cl.ly/image/0g2M1F132f2z

And the second/duplicate style item in the dropdown is coming from my CSS file, which obviously has this: http://cl.ly/image/2j21341N0l1Z.

Any ideas what I've done wrong to end up with both of those items in my style list?

Thanks in advance!