Without knowing your situation, nothing beneficial comes to mind unless your wanting to switch power sources from one battery to the next (I.e. have a switch located in each battery’s positive circuit to disconnect the load and transfer to the next battery).
What you are describing is a parallel circuit. It doesn’t matter if you connect the two (+) and two (-) leads at the battery or at the end device, it’s still parallel.
The problem with the setup you describe is voltage drop. Voltage is pressure in the electrical sense. Therefore, higher pressure always wins. If you have two sets of power wires that are of different length and/or AWG, they will almost certainly have different wire resistances. Therefore different voltage drops. When the end device (whatever load you’re powering) is turned on, the supply with the higher voltage will always win and you will not be equally loading each battery.
Will it work? Yes. Would I do it? No.