No idea why, but in my firewall/advanced many programs have at least two references. AH3 for Dx11 and Dx9 both have two. It may be that one is an older version in which case resetting should remove that.
The resetting in itself is very easy: Simply go to Settings, search for Firewall and in the main window where it lists Domain, Private and Public networks there's a link in the bottom saying Reset to defaults.