Hi Duncan,
We have a PHP script that we've used in the past to delete extra "ghost" rows in the database. To use it:
1) Backup your database! See:
https://www.qubit-toolkit.org/wiki/Data_backup#Database_backup for instructions on backing up a MySQL database.
2) DO NOT proceed unless you've successfully backed up your Data! This script deletes data from the database, and restoring a backup is the only way to retrieve the data. The script should
not delete any "real" data from the database, but there may be bugs with the script that we have not identified.
3) Download
https://github.com/djjuhasz/random-scripts/archive/master.zip and unzip it
4) Move the file "delete-corrupt-qubit-rows.php" to a directory within your web root
5) Open the delete-corrupt-qubit-rows.php script with a browser
6) Fill in the MySQL credentials and click "delete"
The script will output the results to your browser. Make sure to delete the "delete-corrupt-qubit-rows.php" after you are done using it, or move it outside your web root.
Regards,
David