You missed this bit (emphasis added): > You could then press a "copy" key and it would copy one character at a time from the second cursor to your current edit

You missed this bit (emphasis added): > You could then press a "copy" key and it would copy one character at a time from the second cursor to your current editing position Each time you pressed the "copy" key it would literally advance both the main cursor and the copy cursor by one character, with the copied character appearing under where the main cursor just was. To copy multiple characters you would need to press the copy key multiple times or hold it down to trigger autorepeat (even then you would see this process gradually happening until you released).