Yeah, that's weird. There are several forum threads like thisand this, but it doesn't seem to cover the behaviour of global plugins. I'm just speculating, but I wonder if the plugins have a 'priority' for checking a certain type.
For example if we replace Keyboard | Space is down with Touch | Is touching Sprite:
.. Then hold down the mouse button, go over the Sprite, it will be destroyed.
However, Keyboard | Z is down doesn't work any more, but Touch | Is in touch works fine. It's almost like the plugin itself was 'picked' (like a SOL), but not really.
As a workaround, you can separate the conditions.
Of course, you could write it another way: