different background colors in ckeditor in same page

I have multiple instances of textareas on my page, where i want to include ckeditor. On some of them i want the body background to be default (white), and on some of them i want the body background to be black.

To solve this i have installed 2 instances of ckeditor, one is configured with default background color, and the other is configured with black as background color.

I include both instances of ckeditor at the top of my page, like this:

<script type="text/javascript" src="ckeditor/ckeditor.js"></script>
<script type="text/javascript" src="ckeditor_black/ckeditor.js"></script>

Then, when i want to implement ckeditor in the textareas, i do something like this:

<textarea name="content" class="ckeditor"></textarea>

My question is now:
When i implement ckeditor in the textarea, is there a way to tell ckeditor, which js file to use, so i can get the correct background color into ckeditor/textarea ?