Hey Wayne
I'm in melb too, no joke there was a massive crackdown not so long ago in my area of 'monkey bikes' and even mobility scooters with old folk drunk or off their heads high on perscription drugs
Anywho, if you look at the vicroads law you can only run a single motor with a max output of 200W and max speed of 25kph without pedalling.
Lol that would never make it up any hill!!
The power ratings are that low because of ~50cc engines putting out that power.
If the cops notice you have 2 motors then you might be in trouble, but its just a unregistered vehicle fine around $500. They might also get you for not having an appropriate license.
But --- If you tell them that the MAX output is 200w and the top speed is 25kph they don't actually have the equipment to test it.
Lol so long story short, if you ever get stopped (which is extremely unlikely unless you have a petrol motor) then all you have to say is the max output is 200W and you are sweet.
This will be a completely different story should you crash into a car or person, and TAC are involved. This would be worst case scenario. If you are hurt in this instance then you are not covered for anything, plus are accountable for all of the damages caused by the accident.
On the plus side -- the cost of current measuring equipment and training police and road traffic officers was far too high to implement. I have heard this straight from the department of vehicle infrastructures mouth lol
So keep on biking with your "Dual 100W setup" haha and make sure you don't run into anything and you will be fine