Bug 503009

SUMMARY
Digikam doesn't indicate already uploaded images as being present. A record is present in the `DownloadHistory` table.
When it uploads an already existing image, it doesn't show the `has already been uploaded` mark on the import dialog screen when done. No duplicate image seems to be present in the album nor on disk. BUT the `DownloadHistory` table now lists TWO records for this image with DIFFERENT hashes.

This behaviour is inconsistent between uploads. A previous upload maybe handled without problems. The next has this problem. So it is difficult to reproduce clearly. These steps are based on trying to see why images were indicated as not being downloaded.

STEPS TO REPRODUCE/happened
1. Add images option with a local directory with new images to add to the album. Type *.HEIC (iPhone) 
2. 'Download all' -> images are processed. With `Date-based sub albums`
3. Album and images are present when done -
4. Re-visit `Add images` with the same directory
5. All images are shown as not being downloaded before
6. Focus on one image -> DownloadHistory entry exist for it
7. Select the image to download again and download it -> icon indicator doesn't change: still `not downloaded before`
8a. DownloadHistory contains TWO records for the same image name and details with DIFFERENT hashes
8b. NO duplicate image has been downloaded as there is no duplicate file in the album (on disk) or in the album overview
9. Re-visit `Add images` with the same directory AGAIN
10. NOW the specific image IS indicated as being uploaded before

I am aware that DK is not able to de-duplicate already existing images which are not downloaded with the tool. In this case images are downloaded from the same folder from a different machine: e.g. it is the identical source.

It is unclear to me how the hash can be used to track relation in other tables. 

OBSERVED RESULT
Already downloaded image not being detected
Duplicate entries in Downloadhistory tabel after 2nd download with DIFFERENT hashes (same name, size, date)

EXPECTED RESULT
Images being indicated as downloaded when present in (any) album
No duplicate entries in Downloadhistory table for the same image

SOFTWARE/OS VERSIONS
macOS: 15.5.1 with Digikam 8.6.0

ADDITIONAL INFORMATION
MariaDB: 11.7.2-MariaDB Homebrew 
Images located on a Linux Ubuntu 24.04 server