The id that no longer exists after the merge.
Loser PDFs that filled a PDF-less winner version — renamed in, or pointed at in place when they cannot be moved.
Duplicate loser PDFs unlinked after commit.
Duplicate loser PDFs left on disk because they live outside the managed PDF dir.
Loser versions whose stored PDF path had no file behind it (transplants/adoptions found gone pre-rename, duplicates found gone post-commit).
Loser PDFs renamed to winner on-disk names in the managed dir.
Tags the loser carried that the winner didn't (now unioned in).
Loser versions collapsed into the winner's same-numbered versions.
Loser versions the winner lacked, re-keyed under the winner (same version numbers).
Loser memberships dropped because the winner was already in the project.