extra ins in vst~ - what for?

hi

I use Native Instruments Guitar Rig quite often. I recently switched to Guitar Rig 5 (I was using 3 so far)

when I create a new vst~ object and load GR inside (3 or 5) it is created with 2 ins - and works well

when I create the [vst~ "Guitar Rig 5.vst"] object (the plug-ins are in my search path) it creates an object wit FOUR ins (and works well)

___what is the purpose of those 2 extra ins? I could not find it in the documentation

thanks

kasper