A two launch mission is very much being considered for Mars sample return:It would be interesting to see the currently planned mission profile of Chinese Mars sample return mission. The previous tentative mission profile China published involved the use of a single huge (mass at earth departure = 30+ tons) and extremely complex probe that requires the use of the planned long match 9 rocket to lunch. If that mission profile is still current, then it means LM-9 has to be in service by that time.

This one here for example calls for LM-3B to launch the lander and ascent vehicle while LM-5 launches the orbiter and return vehicle.