They can both be the same resistor, it just means the 12V input will have more overdrive........................
I do have a question ... Should R2 and R3 both be 10k ohms? I ask because there is a 7 volt difference to trigger the circuit.
You want the base current to be 1/10 or more of the collector current to fully saturate the transistor, and that is met for both inputs with 10kΩ resistors.
You can increase the 12V input resistance if you want to, but there's no compelling reason to do so, unless you want to save a few tenths of a mA of current.