I once asked CX agent if there are any way to get GV2 fares both under my name. answer was plain no... they said I had to be travelling with 2 people..... I said what difference does it make for me to buy both tickets and travel alone with 2 seat and the agent on phone failed to grasp my mentality.

as someone said above, you can do it, but with lots of special arrangement. Furthermore I'm not sure if the extra seat for musical instrument will be full-fare or same discounted fares.