Citations for categories

I’m getting numerous error messages from the W3C evaluation program that indicates there are “Duplicate attributes” being cited with the “rel” tag for various categories. Here is a sample of one code that is apparently causing these errors: “<span class=”category”><span class=”icon”> </span>Does, Lives, Wants</span>” I understand that WP would prefer to have each post cited in only one category, but I haven’t defined my categories in such limited specific citations. So how should I cite these attributes for my categories in each of my posts in order to avoid creating these errors in my codes? I would appreciate your instructions for doing this. Thanks.