Photoshop Elements 2023 organiser, recognising backed up photos

Hi Marcus.  The answer to your question is   . . . .   it depends.  So, it sounds like this the first time that you are using Elements.  If so, consider the following explanation.

• The Elements Organizer is a database that keeps track of the photos on your computer wherever they are stored.  It does not make new copies of your photo files unless you are importing them from a temporary storage device such as a camera memory card or phone.
• Once you have imported the files (in your case, from your C drive), all further file management (copy/move/delete) should take place within the Organizer rather than through your OS such as Windows File Explorer).  Otherwise, the Organizer cannot keep track of what you have done with your files.
• Because the Organizer is only a database, (in theory) it will only keep track of one copy of a photo.  So, if you have identical files backed up on your external drive, it is likely that if you tried to import them to the same catalog as the files stored on your C drive, you would receive a message that the file already exists in the catalog and will not be imported again.  There are many possible exceptions to this rule, depending on how you backed up the files to the external drive.  For example, some backup programs may rename the files and you would be able to import the renamed file to the Organizer.  But if you do so, you will likely lose much of the database information such as tagging and face recognition, that have been applied to the original file.
• However, the Organizer has its own backup utility which will back up the database (catalog) information as well as the photo/video files stored in the catalog.  If your original files become corrupt on your C drive, you would be able to restore the Organizer's backup and all of the database information created up to the time of the backup will be restored too.
• If you are talking about restoring single files from the backup on your external drives, I would recommend using some kind of synching software which keeps track of any changes to your files and updates any changes you have made on the original to the copy.  Then, if you had a corrupt photo on your C drive, you could replace it with the updated file on your external and all tagging and metadata should be preserved.
• Elements 2023 also allows you to make automatic backups of your catalog/database files only.  If the catalog becomes corrupt, Elements will automatically restore the last saved copy.  However, this is one case where you can use the OS to copy the catalog folder to another drive.  (A 7,000 photo catalog does not take up much storage space and can be easily copied.)  You can even open the copied catalog from its new location and it will still be able to refer to the photos stored in their original location.

You are right to be concerned about corrupt files and it is always a good idea to make multiple backups of your precious photo/video files.  Hopefully, I have not confused you too much.  Let us know if you have any further questions, or if my premise about your prior experience with Elements is wrong.