No, but for whatever reason the Isolated Ground Conductor was installed for in the first place, it will not have this isolation after using it for a plane jane EGC.
Many times the isolated ground is pulled through one or more panels back to a main panel.
Do normal ground wires have to originate in the same panel as the branch circuit or feeder it's ran with? Maybe I am confusing ground wires with neutral wires?
I wonder if the isolated ground was originally installed at the insistance of an equipment manufacturer so that the equipment would work right and it didn't make any difference.