Using the error log file created by script that removes duplicate email message

I have just run the Apple Script published here Remove Duplicate Messages - EagleFiler AppleScripts. Before running the library file contained sixty thousand messages and when complete the script reported removing eleven thousand of them.

Towards the end of the run the script reported an error log with the option to Ignore Errors or Cancel. I chose Ignore and the script completed. I have looked at the script but I don’t understand what the difference isbetween the two options:

on reportErrorsFromLogPath(_logPath)
    -- Skip lines starting with "<" becuase they are probably a wrapped message ID
    set _script to "grep -vEc \"^(\\s*<|formail: Duplicate key found:)\" " & _logPath's quoted form
        set _stdout to do shell script _script
        set _errorCount to _stdout as number
    on error
        set _errorCount to 0
    end try
    if _errorCount > 0 then
        do shell script "open -a Console " & _logPath
        set _title to "Possible Errors Reported"
        set _message to (_errorCount as string) & " unexpected log entries were found when processing the mailbox. Please review them in Console."
        with timeout of 24 * 60 * 60 seconds
            display alert _title message _message buttons {"Cancel", "Ignore the Errors"} cancel button 1
        end timeout
    end if
end reportErrorsFromLogPath

Any thoughts ?

Also I am uncertain how I use the information presented in the log file :

formail: Duplicate key found:<BLU159-w25DCC01101B0F78DD802B4BEC30@phx.gbl>
formail: Duplicate key found:<BLU159-w15A14B185BE4FA81AB3C1EBEC30@phx.gbl>
formail: Duplicate key found:<BLU159-w49A078778EE6EE45453456BEC60@phx.gbl>

Am I able to search for the record keys ? I can’t search at the moment as the index has not been rebuilt and I suspect it will take the rest of the day to complete as I am using old hardware : MacBookPro Late 2013 Quad Core i7 and the script took over fifteen hours to complete (time for an M2 perhaps)

best wishes

The errors in the log would be the lines that don’t say Duplicate key found.

As Reacher would say “good to know” . Thanks.