yeh usually when players become "greats of the game" or close to it, you see a variation within their sigs.
One cricket player i know is Gilchrist, have seen his full version and small version, but most of the time he signs full though which is what i got from an ip, but have seen smaller ones on ebay etc which are legit.
Other sports - Chris Judd, Ben Cousins all players who have an official sig and a ip sig that got shortened once they became stars!