LR doesn't recognize duplicate when file copied to another location

[rjphoto2]

I have older files (jpg about 20 yrs old) and when I copy the file using OS to another part of storage LR doesn't recognize it as duplicate. Win 11, latest version LR classic on desktop. Big problem when found some missing pictures and reloaded from backup drive, like 2000 picture problem.

Number of previous similar posts but all seem to stop without solution.

yes do not import duplicates checked. Yes it is the same picture copied with operating system.

suggestions?

[rjphoto2]

additional information. If I do import from the folder in the LR catalog LR recognizes it as duplicate. If I copy the picture to another folder it does not recognize the picture as duplicate.

[GoldingD]

Let me see if I understand your steps, or perhaps I am assuming something.

• You have existing photos, In this case JPEG files already imported into your catalog
• Outside of LrC you use your OS file manager, in this case MS Windows File Explorer, to Copy many of those photos to another hard drive, ore folder. That is COPY, not Move.
• You have not instigated an import in Lrc, nor a Sync folder in LrC in regards to those copy's.
• The photos you originally imported into LrC still show up in the catalog.
• The copy's do not show up in the catalog.

[rjphoto2]

yes - I agree

that is not the issue

Picture in my catalog. Copy that file to another location. Import the copy (not a moved file) from new location and LR does not recognize it as a duplicate. This is for my older jpg. It works as expected for an recent HEIC picture. 

JPG from 2020 it does not recognize as a duplicate. Again copied picture from one place on storaga to another folder same storage device and LR did not recognize as a duplicat