Hi,
You need a MySQL query, which you can easily run from any tool, even phpMyAdmin if your host provider has that in cPanel. If you insist on a PHP script, then that script will just contain some mundane code with database credentials, and run the de-duplication query.
Questions:
1. Is that the specific table required?
2. Are those the exact field names to de-duplicate against?
3. Is this a one-off - you give me credentials, I run it once - or is this script something you want to run over and over again in future?
Regards,
Richard