I'm thinking that normally circuits are conducted on runway right (31 & 35). Are first solos conducted on 31 Left due to less intense traffic? Airport management is saying they had both recently taken off, which points to circuits but could just have easily have been the Warrior re-joining. If it was circuits you'd think the Warrior would have out performed the 150 and been ahead of it.
I'm just suggesting that if they were doing circuits they were very unlucky based on the performance of their respective aircraft types.
Reminds me of the recent crash at Latrobe Valley where a very low time Indian solo student ran into the back of another aircraft and killed the pilot of the preceeding aircraft.
Whist we always say Aviate, Navigate and then Communicate, both these incidents are having the finger pointed at Communication breakdowns.