Yes, the hotswitches are mutually-exclusive. Selecting one toggles the other off, as it ‘can be’ a combination of parameters from both Presets. It doesn’t ‘have’ to be, but it is a Program-level command.
Something cool, though, is that Performance Parameters persist. That is, you can latch them on & off, independently of hotswitch actions.
For example, a Performance Parameter specific to Polyphony, like FREEZE, remains active through the hotswitch toggling.
