How to list an image twice in a pool?

For pool #6812: presently, many characters are supposed to ring Homura's doorbell, one at a time.
For each encounter, the artist uses the same image, but Danbooru does not allow the upload of duplicate images.
How do I have the same image appear more than once in the pool without uploading it twice?

The site was updated so that you can now add posts to pools multiple times now. It works like adding a post normally does.

I'm getting the pool navigation problem with duplicate images on post #1795618
The same problem Toks mentioned in issue #2042