In multi split system air conditioners, the indoor units (heat pump type) should be the same (model, capacity, etc)?

In a multi air conditioner system, the indoor units may be the same or different (type, capacity). However, we should be aware of the number of the units that will be connected. Also, should beware of the total capacity (kW) of the indoor units, not to overcome the capacity of the outdoor unit, in case of a simultaneous operation of the indoor units.