If you installed two complete heat pumps to save on and speed recovery,
the added cost of the second system would be more than the savings
provided by not using any strip heat. If you installed a slightly
oversized 2 stage heat pump, it would run in low stage all summer
providing about 65% total cooling capacity. Then it would run in high
stage (High Capacity) during heating season when it was below 45
degrees outside. You could possibly set back in this case. Note that
installing a two stage heat pump usually adds about $2,000.00 to an
average installation. The average life of a quality, properly
installed air to air heat pump is 15-20 years nationally. If you would
save $2,000.00 over that time span, then install the two stage system.
If you install two complete systems, add about $6000.00 to $10,000.00
to the cost of the first system, assuming you had room for the extra
ducts and registers and equipment. Tough way to save money. Like
going around your elbow to get to your asshole. (Or is it the other way
around:-)? ).

Strretch