(defface duplicated-cursor
  '((t
     (:height 151)))
  "Face for frame to illustrate the issue")

(set-frame-font (face-font 'duplicated-cursor))

(defun insert-height (h ascent)
  ;; use a PBM image, due to problems with XBM (see #36337)
  (insert-image `(image :type pbm
                        :data ,(format "P1\n1 %s\n%s" h (make-string h ?0))
                        :ascent ,ascent) "t"))

(defun goto-last-window-line ()
  (while (pos-visible-in-window-p)
    (insert "\n"))
  (delete-char -1))

(defun duplicate-cursor ()
  (interactive)
  (switch-to-buffer (get-buffer-create "duplicated-cursor"))
  (erase-buffer)
  (insert "\n\n")
  (insert-height 160 80)
  (let ((m (point-marker)))
    (insert-height 125 'center)
    (goto-last-window-line)
    (redisplay)
    (delete-region (point) m)
    (insert-height 112 'center)
    (insert "\n\n")
    (insert-height 6 100)
    (insert (propertize "\n"
                        'face '(:height 1)
                        'line-height t
                        'rear-nonsticky t))
    (goto-last-window-line)
    (previous-line)))