I know why there are two. But there are situations where having two does not quite work.
1 - I have an Ibanez TS-10 in the loop. It is sitting before a clean sound. So while distortion sense takes care of all the sounds that the Kemper knows are distorted it thinks this is a clean sound.
2 - I have sounds i will categorize as clean, but since they have a little bit of chrunch in them the Kemper thinks they are distorted.
In both cases the clean/distorted sensivities will not work as expected.
And since i do not really care if i have to turn a volume knob while auditioning sounds one sensitivity would be enough for me. For live use i will level the rigs via rig volume anyway since no software is going to satisfy me in the "finetuning of sounds/levels" department anyway.
(And yes, since i know someone will ask, i do find the Green Scream to be a fine screamer emutation, but the TS-10 is just very different than the TS-9 the Green Screamer emulates.)