[JesseK]

To find the combined torque of two motors, do I calculate the equivalent winding resistance, then back track to the stall torque?

For two identical motors this makes sense since their combined equivilant resistance is half of the original, so the torque is twice the original (which matches up with JVN's super motor specs). Yet some of the other super motor specs don't match up when I approximate the stall torques using the same method. I reverse-engineered each individual motor's winding resistance using unit conversions and a rearranged version of your equation. I'll let this sit for a while and think on it.