jwilliams4:
Not necessarily. Many years age FEDDERS developed a dual coil that fit into a single furnace/air handler, but was operated by two condensing units. It was controlled by a thermostat with two mercury bulbs that would make connection 2 degrees apart. If the first system could not cool the house, the temperature would rise 2 more degrees and activate the second condenser.
Frequently the two line sets were joined in a common conduit and appeared to be a singe installation inside the house.
There was also an occasional attempt to use two small condensers in place of a larger unit (sometimes the cost difference was enough to do this) by joining the two lines into one larger line set. There were about 200 reasons why this didn’t work, but you never know until you try.
I saw a lot of those old 2 stage Fedders units back in the 60’s but they all had only one high side cabinet with two compressors, two condensers, two suction lines and two liquid lines.