I was curious about that too. And I did it! The TS is in 1 block, but you must use 2 footswitches. In Menus, choose controller assign. Scroll to the Tone Sovereign which changes the list of parameters you can select under the #1 knob. Select 'gain 1' and set min to zero and max to whatever suits you. Then choose an empty footswitch. Save. Repeat for 'gain 2'. Save. Now in Stomp mode you will see 2 gain switches and they are independent AND stackable!