That is a file that you will find in your Gimp profile. So I suppose that you will overwrite the existing one.
Not a big deal, if worried rename the existing as a backup. The file is text and starts with this comment
# GIMP sessionrc # # This file takes session-specific info (that is info, you want to keep # between two GIMP sessions). You are not supposed to edit it manually, but # of course you can do. The sessionrc will be entirely rewritten every time # you quit GIMP. If this file isn't found, defaults are used. ....
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