That's correct yes. Both battery packs have a negative (black) wire and positive (red) wire. You connect the black wire from one battery to the red wire of the other and then you are left with an unconnected wire from each pack. The voltage from these wires is now 24V. You connect both your speed controllers to your battery wires in parallel (i.e. each speed controller has one red wire and one black wire. You connect the two red wires from your speed controllers to the unconnected red wire from the battery pack and the same for the black wires). This means that both your speed controllers will get 24V and therefore both motors will get 24V.