We can use a regular size Ku band dish to receive both satellite Optus D1 and D2. Special things needed are one dual LNB holder, a 2-way DiSEqC switch, as well as some proper configuration to the receiver box setting. We can add up more different satellite into one satellite receiver box. A 4-way DISEqC switch for 4 different satellites for example.

This is a regular second hand dish, we put two LNB on, properly tuned. Left LNB is for D2, right center one is for D1 which is Freeview and Sky channels.

Dual LNB holder:

4-Way DISEqC

We can use one dish to keep both Sky subscription channels, Freeview satellite channels and all Optus D2 FTA channels.