Therefore doesn't this mean it was not already there?
You can be sure the font was already there, otherwise you wouldn't have seen the error, which clearly says "trying to replace the existing file". Don't assume anything when the Windows folder is concerned, since that folder has special protection features that can cause all sort of misleading behavior.
Note that, you cannot install a Font by "just" copying it to the Windows\Font folder. The correct way to install a font is:
- copying it from another computer in a normal folder, like your Desktop.
- double click on it to INSTALL it. No, that's not just a simply copy, it's a registration of the Font in the registry as well, the font won't work if it's just copied
- after the font is installed, you can remove it from the place you copied from ( the Desktop, in this example )
Not that you *have* to do all of this. The GSX installer does EXACTLY that but, as I've said, in some cases that error message appears, and you can ignore it.