mc/region-strings が期待してたものと違ったのでこんなの作ってみました

(defun my-mc/all-region-strings ()
(let* (strings
(cursors (mc/all-fake-cursors))
(tmp-list (and cursors
(let ((lst (list (list (mark) (buffer-substring-no-properties (point) (mark))))))
(mapc #'(lambda (x)
(let* ((beg (mc/cursor-beg x))
(end (mc/cursor-end x))
(str (buffer-substring-no-properties beg end)))
(setq lst (append lst (list (list end str))))))
cursors)
lst))))
(when tmp-list
(setq tmp-list (sort tmp-list #'(lambda (a b) (< (car a) (car b)))))
(mapc #'(lambda (x)
(setq strings (append strings (list (car (cdr x))))))
tmp-list))
strings))