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