Load https://musicbrainz.org/release/c5355b3d-3f53-4388-90c5-f51e40182462?tport=8000 (possibly with the config from PICARD-1001), save it. Note how only a single front image is shown in the cove art box. Remove it from Picard, disable all cover art providers except Local Files. If not already there, add "|front" to the local files regular expression, so it looks like ^(?:cover|folder|albumart|front)(.*)\.(?:jpe?g|png|gif|tiff?)$. Load the folder the release was just saved into. Picard now shows two images in that box.