For those that would like to rid themselves of this problem, there is a really easy solution that is working 100% for me.
FIRST: Figure out the exact string that Dreamweaver is generating for the META Content Type tag... It will be different depending on your setup. Just create a new page and see what is being generated. In my situation it is the same as Dave's "<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />", but yours may differ.
SECOND: Open: webasssit > framework > framework.php
Near the bottom of the page, you will see some entries starting with: "head=preg_replace......"
THIRD: In that mix of entries (I put mine just before those begin) add this line (remember to replace my string with your string):
$head=str_replace("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\" />","",$head);
RESULT: That removes the EXACT string if it is found, only on the included pages... No more duplicate "Content Type" meta tags. You can add more than one entry if you want or need...
NOTE: str_replace is a lot faster than "preg_replace" which is why I went that route but it only works with exact strings. You could use preg_replace and write a regex that matches any "Meta Content Type" pattern...