I can only speak for the situation in Queensland, but imagine it is very similar in Victoria:
It is completely usual and, in fact, is the only way the land can be dealt with. Deceased persons cannot be the owners of land - or anything else. The estate, being the sum of everything the deceased person had, must be administered by a trustee or trustees on behalf of the ultimate beneficiaries. In the situation of a deceased estate these trustees are called executors or, once probate or letters of administration have been granted by the Court, personal representatives - but let's use executor to keep it simple.
While the executor is given legal title to the property, and are therefore the registered proprietor, they do not own the beneficial title to the property. That belongs to the ultimate beneficiaries. In very broad and simplistic terms, having 'legal title' means you have all the formal rights and responsibilities for the item - having the beneficial title means you get all the usefulness out of the item without having to worry about the formal requirements. Consider it this way: Imagine you have a car. The legal owner is the driver of the car, the beneficial owner is the passenger, and the legal owner is required to drive the beneficial owner wherever they need/want to go. So, while the legal owner has to pay attention and obey the road rules, the beneficial owner can put their feet up and snooze.
The fact that the people are registered proprietors in their capacity as executors gives notice to everyone that this sort of 'trust' arrangement is in place. The executors are then required to administer and deal with the property in accordance with the terms of the will.