I don't think it will happen in Melbourne... the capacity is too large. Think it can hole about 50-60,000. Is sydney's capacity much smaller?
As for getting a 2nd day, you going to that? I would SO go to both. Then I wouldnt have any clashes!!

So I am happy if the same thing happens in melb. Given it would mean putting the BDO on a weekday or another weekend (they come back) it may not happen at all. So I will definitely have to get a ticket. I'm actually tempted to go to Sydney's 2nd show as well.. its on a sat, and it's the 100th BDO ever...