+(defcustom flyspell-mark-duplications-exceptions
+ '(("francais" . ("nous" "vous")))
+ "A list of exceptions for duplicated words.
+It should be a list of (LANGUAGE . EXCEPTION-LIST). LANGUAGE is matched
+against the current dictionary and EXCEPTION-LIST is a list of strings.
+The duplicated word is downcased before it is compared with the exceptions."
+ :group 'flyspell
+ :type '(alist :key-type string :value-type (repeat string)))
+