flyspell-highlight-duplicate-region

flyspell-highlight-duplicate-region is a compiled Lisp function in `flyspell.el'.

(flyspell-highlight-duplicate-region BEG END POSS)

Set up an overlay on a duplicate misspelled word, in the buffer from BEG to END.
POSS is a list of possible spelling/correction lists,
as returned by `ispell-parse-output'.