issue #2584 - also finds duplicates on same file

dev/translation/sanity_check_en_langfiles.php

@@ -47,7 +47,7 @@ foreach ($langstrings_3d AS $filename => $file) {
 		$keys = array_keys($langstrings_full, $value);
 		if (count($keys)>1) {
 				foreach ($keys AS $key) {
-					$dups[$value][$filename] = $linenum;
+					$dups[$value][$filename][$linenum] = '';
 				}
 		}
 	}