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.