I'm not sure if you can say none of them do. Look at this 12th century Coptic icon:
But a lot of Coptic icons I have seen have the one-finger gesture, like this:
I'm pretty sure the icons in my church are all like the second type, and if I had to guess, it's a manner of making the icon to conform to our Christology just as the Byzantines infused what was apparently originally a secular gesture with theological meaning according to their Christology. Just an idea. I welcome correction, since I don't really know much about iconography (that's why I went to the OCA talk in the first place).