adds <![CDATA[ to html page

I’m not sure if this is a bug or not but when I try to ad google adsense code of the form to a page post

<script type="text/javascript"><!--
google_ad_client = "pub-3--------";
/* 468x60, created 2/15/10 */
google_ad_slot = "94--------";
google_ad_width = 468;
google_ad_height = 60;
//-->
</script>
<script type="text/javascript"
src="https://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>

it then adds extra code that weird look

<script type="text/javascript">// <![CDATA[
 google_ad_client = "pub-3--------"; /* 468x60, created 2/15/10 */ google_ad_slot = "9--------"; google_ad_width = 468; google_ad_height = 60;
// ]]></script>
<script src="https://pagead2.googlesyndication.com/pagead/show_ads.js" type="text/javascript">
</script>