Then what temperature would be twice of 0F?All you did here is show that there are different scales/units of measurements for temperature. Farhenheit, Celsius & Kelvin. They don’t scale 1:1 relative to each other. If you say the temperature went from 50F to 100F it then did in fact doubled in temperature relative to the Farenheit scale; not so much when compared to the Celsius and Kelvin scale. It’s all RELATIVE to the system you’re using.
I cannot think of another system that scales in differences quite like these temperature scales, most everything scales evenly 1:1 relative to each other.