Products.TinyMCE 1.3.9 , css resources are loaded twice in the iframe

[fredvd]

I was inspecting some styles in the TinyMCE editing area and noticed in the css inspector of my browser that all definitionsare there twice, with one strike through. Further inspection shows that in the section of the iframe all css resources are loaded twice. Fresh Plone 4.3.4 site:

<base href="http://localhost:9020/testsite/">
<meta http-equiv="X-UA-Compatible" content="IE=7">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<link type="text/css" rel="stylesheet" href="http://localhost:9020/testsite/themes/advanced/skins/plone/content.css">
<link type="text/css" rel="stylesheet" href="http://localhost:9020/testsite/portal_tinymce/@@tinymce-getstyle">
<link href="http://localhost:9020/testsite/themes/advanced/skins/plone/content.css" data-mce-href="http://localhost:9020/testsite/themes/advanced/skins/plone/content.css" rel="stylesheet">
<link href="http://localhost:9020/testsite/portal_tinymce/@@tinymce-getstyle" data-mce-href="http://localhost:9020/testsite/portal_tinymce/@@tinymce-getstyle" rel="stylesheet">

Is this done intentionally?