Deen Doughouz why I get error log file all the time and the following error inside

[11-Sep-2017 049:50 America/Los_Angeles] PHP Warning: Module 'PDO' already loaded in Unknown on line 0

Each time I delete this error log file from my root folder it comes up again with the same error. Each time I visit any page of my site this error log file grows & grows even up to 7 MB I saw and I am keep deleting

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