This might be difficult to type out but I'll do my best.
I am trying to convert some financial documents to the current fiscal year, and in order to do so I need to change file names. No matter how many times I duplicate the files, they are still sourced to the original document, which we need to keep for our records. How do I create a duplicate that is only sourced to said duplicate so that I can change file names and keep our records from getting sloppy?

With the duplicated file active, choose the Data tab, and in the Connections Area  choose   Edit Links    and then choose Change Source.... and change the source to the duplicated file.