If you duplicate a page, quickly check the page settings, specifically the page description. This field becomes part of the structure of the page and is called the meta-description field. This is the field that Google uses to help index the page properly.
Also, Google may, and does often, return this field in the search results. Therefore, the page description should be accurate for the page. If you don't know what the page description field will be, write it down to bring up as a point before go-live, then empty the field.