P: Automatically edit meta data without copy or paste

I use a programmed call ENTAGGED for GotPhoto to sell portraits.  The program automatically writes a barcode into the the meta data copyright field so that when it is uploaded to GotPhoto, it will automatically sort into galleries created by the barcode.  

I like to 'rename' files in lightroom with the copyright data where I've previously appended a "name" to the barcode in Excel.  This way when the file writes to the copyright field the name and barcode are there.  This is good for "naming" files in LR but not for uploading to GotPhoto after edits are made.  GotPhoto can only read the file if I remove the name from the Copyright field and leave ONLY the barcode.  It's a 2 step process but I cannot manually cut and paste per image to remove the name.  I'd like to know if there is a way to ask LR to remove all data to the right of the barcode that is separated by an underscore "_".

{Barcode}_{child first and last name}