there are more than 100 duplicate antries in language files (ie, the same language constant defined in more than 1 file).
since they are so many, i dont list them all here, but i will list the summary:

Equal: 77, Differ in case only: 10, differ in content: 27

this means that 77 of them having equal value in 2 files (example: CLOSE_WINDOW in common.php and posting.php), 10 differ only in case (example: POST_DETAILS in common and mcp), and 27 actually differ (example: SEARCH_KEYWORDS in common and search).