Use the shareware app Find Any File to search for the file:
1 - Name contains XXXX
FAF can search areas that Spotlight can't like invisible folders, system folders and packages.
You would be best served to view the image in QuickLook and then try to find it in the Library proper to delete it. Otherwise you may damage the library so that you can't do a mass export, print, project or whatever if that particular file is in the group being worked on.
Another way to do the job is as follows:
1 - copy the file to the Dsktop.
2 - open with Preview and save with a new name: Test.jpeg or similar.
3 - import the new file into the library.
4 - use PhotoSweeper - $9.99 to search for duplicates. Since it looks at the bitmap or histograms for comparison it will find duplicates even if they have different creation dates. file names and file sizes.
When it finds those two files you can delete the one that doesn't have the name you gave the replacement.