If you add a internal link with GET parameters, the & character will be escaped twice.

Steps to reproduce

Edit an article and add a link in a field with the ezxmltext datatype, like the summary or the body:

<link href="/index.php?c=6&kat=company">My link</link>

will output:

<a href="/index.php?c=6&amp;amp;kat=company" target="_self">My link</a>

when you view the article on the user side. A link with GET parameters in a link with http:// in front works fine.