It helps to mirror and create simmetrical BlendShapes.
Parameter 'Mirror' allows just mirror blendshape. If 'mirror' off plugin remains deformations and add simmetrical one. Example: You can 'close' one eye on head model and apply plugin with
turned off 'Mirror'. Result: both eyes are closed. You can create smile very fast. Just deform one side of the mouth and use plugin to get other or get simmetrical shape.