Any 2-way(or more)speaker has the high and low frequency sections separated at the latest when the signals enter the crossover. Using dual inputs with the connecting bar removed, the separation point is simply moved back from inside the enclosure to the output terminals of the receiver. This makes no electrical difference as to impedance or anything else of significance.
If two 120 watt amplifiers are connected to separate sections of a speaker, the maximum available to either section is 120 watts, not 240 watts.
See!! this stuff is so confusing. Far better to stick to one amp, plug it in, turn to 11, enjoy.