That doesn't sound right (well, Qantas did have RR engine trouble, as did all RR engined A380s) as all A380 fleets have four of the same type/manufacturer of engine (RR or GE, depending on the airline) and it will be common across all the planes in the fleet. It doesn't make sense to have to double up on maintenance costs, equipment and engineering staff with two types, plus the added risk of a GE bolt/whatever accidentally fitted to a RR engine causing an accident...