[PAID] Custom Rule using Rules Automation

[Music Case 13]

Hello, I currently have a custom data field via Rules Automation which allows for the input of an IMDb ID and I'm wanting to automatically send a notification of duplicate content. I'm needing a custom PHP rule where if string 1 exists already in database a notification is sent to the user. I'm currently using Rules Automation as a condition: String 1 is the same as String 2 but again I need the php to select string 2.

I'm happy to pay for the help on this.

Thanks.