Survivor Australia

Watching first dead lock vote sending Mitchell out because he had more votes in a previous tribal. This is my first time watching these earlier seasons (I watched 9-14 and now watching 1-8 in order). Anyway I’m curious as to when the deadlock switches to purple rock which we know in present day. Also considering it was so early on in the game, if Mitchell hadn’t received a vote in previous tribals I wonder what would’ve happened in that instance?