If you vote outside your local area there is extra steps and you need to let them know. They usually ask everyone; “if you’re voting outside of area”, join this line.
Extra verification and proof is needed if outside of area. I think behind the scenes, the fact you voted out of area is communicated back to your area.
Voter fraud is very low in Australia. With compulsory voting of all ciztiens, the quantity of votes is very high. We have 98% of the population enrolled to vote fyi.
So with these quantities, the incentive of say double voting fraud is greatly reduced.