For convenience sake let’s say you have 2 identical lasers, one is blue and one is red. And you shine it on lead (so none of the light leaks through) until the lead doesn’t heat up anymore. Would the temperature change at all between the different color lasers. It doesn’t have to be red or blue, it could be microwave or x ray, just different colors is nessisary.
That’s not really necessary. Lasers are usually rated by the output power already.