wysiwygPro is software that is used to create webpages online with a text editor type screen and is usually used with Blog software, CMS, etc, so they may be a part of some other software you have installed on your server. At a guess I reckon they are temporary cache files (this is just a guess) as from the name suggests it is for previewing and editing using wysiwig pro. You can visit the wysiwygPRO website:
http://www.wysiwygpro.com/index.php?id=55If you are worried have a look at the code and paste the code here. I'm not that good with PHP but can understand wee bits, other people here might be more knowledgeable with PHP and give you a better answer.
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