You're overanalyzing this.
You got the right calculation and you performed it correctly. At 1.8 amps these lamps by rights will burn 1.8(Amps) * 12(Volts) to get you 21.6 Watts per lamp.
You received a mildly snarky response suggesting that if you double it and round up you'll get to the model number (21.6 * 2 = 43.2, round up and you get 44) . There's not much more to it than that.
I have no idea if the model numbers are related to power consumption in real life, or if it's just an amusing coincidence.
Why did I drink all of the ingredients for vomit?
"Used to be Man vs. Nature.. then Man vs. Space.. then Man vs. the Moon. Now it's Man vs. Food" - Dalar
"you cannot reason a person out of something they were not reasoned into." - Jonathan Swift