If you are a requester:
Often in the article creation process we don't see that a similar or exacting article already exists. This leads to duplicate pages. If you find two (or more) such pages, add the "[[Category:Merge]]" tag to both (all) articles and our editors will merge the information together into one page.
If you are an editor:
Merge all pages listed and also try searching for any additional unlisted duplicates. Leave #REDIRECT commands as appropriate. When your work on that article(s) is complete remove the "[[Category:Merge]]" tags from all applicable pages.