When you duplicate a page, everything on the page you are duplicating gets copied to the new page. However, what you have to be careful of are elements you add to the top and bottom global areas. These will also get copied, but if you remove an element from either of these two areas on any page, they will be deleted from all pages. Things you place in the dynamic area can be removed from duplicate pages without affecting any other page in the site. From the description of your issue it sounds like you may have placed content in the global areas which you are trying to delete from duplicate pages. So, only put content in the global areas if you want it on every page. If you don’t want common content on every page, don’t use the global areas - place all your page elements in the dynamic area only.