Take a look at some website templates; they have.
The thing you SHOULD change on every page is your content! but a few sentences don’t harm, just not an entire article!. The search engines have no issues with this and if you have been reading, I have already pointed out that the search engine spiders ignore code anyway to some extent. Take a look at some website templates; they have code that is EXACTLY throughout the site. You don’t need to change the code in your pages to avoid duplicate content problems.
Original text search at: www.directoryofseolinks.com/blog/2008/04/