Bellow is the patch for the trunk version, without cl-remove-if-not

diff --git a/lisp/image-dired.el b/lisp/image-dired.el
index bbb41d4..2e169ed 100644
--- a/lisp/image-dired.el
+++ b/lisp/image-dired.el
@@ -657,16 +657,24 @@ previous -ARG, if ARG<0) files."
                 (string-match-p (image-file-name-regexp) image-file))
        (setq thumb-file (image-dired-get-thumbnail-image image-file))
        ;; If image is not already added, then add it.
-       (let ((cur-ov (overlays-in (point) (1+ (point)))))
-         (if cur-ov
-             (delete-overlay (car cur-ov))
-   (put-image thumb-file image-pos)
-   (setq overlay
-                 (cl-loop for o in (overlays-in (point) (1+ (point)))
-                          when (overlay-get o 'put-image) collect o into ov
-                          finally return (car ov)))
-   (overlay-put overlay 'image-file image-file)
-   (overlay-put overlay 'thumb-file thumb-file)))))
+       (let (( cur-ovs (overlays-in (point) (1+ (point))))
+             thumb-ov)
+         (while (and cur-ovs
+                     (if (overlay-get (car cur-ovs) 'thumb-file)
+                         (progn
+                           (setq thumb-ov (car cur-ovs))
+                           nil)
+                         (pop cur-ovs))))
+         (if thumb-ov
+             (delete-overlay thumb-ov)
+             (progn
+               (put-image thumb-file image-pos)
+               (setq overlay
+                     (cl-loop for o in (overlays-in (point) (1+ (point)))
+                              when (overlay-get o 'put-image) collect o
into ov
+                              finally return (car ov)))
+               (overlay-put overlay 'image-file image-file)
+               (overlay-put overlay 'thumb-file thumb-file))))))
    arg             ; Show or hide image on ARG next files.
    'show-progress) ; Update dired display after each image is updated.
   (add-hook 'dired-after-readin-hook