How do I correctly estimate heat output for heater wire
Your calculation appears to be correct, assuming the wires were the same dimensions. In practice, the lower resistance one would tend to be larger, so it would run cooler. 

However, I doubt your measurement, so I would call the calculation based on it into question. 

The figures I use show a maximum current of about 11A for AWG 24 copper wire (actually a bit higher resistance than yours) and allowing a temperature rise of 125°C .. for a single wire in open air at sea level (best possible case). In practice because you usually have to allow for higher ambients, more wires in close proximity and possibly higher altitude and (often the dominant concern) less voltage drop you can't get anywhere near that current. AWG 24 is also too frail to leave flapping around in applications involving vibration.