I have a page where the latest posts are displayed from within a specific category.

array( 'posts_per_page' => -1, 'post_status'=>"publish",'post_type'=>"post",'orderby'=>"post_date",'order'=>'DESC','cat'=>"5")

Within this I would like to only show the latest post for each tag. I don’t know if this is possible but I’m hoping I’m wrong.