You can add a Face Mask of an original face over another Face Mask by enabling Use Orig. Face on your second Face Mask so that it renders the face rather than a texture. Then, set the Texture field on the Face Mask to the Device Camera Texture so that it displays the face before the previous effect.

Pro tip 1: By default Lens Studio renders objects in the order they are listed in the Objects panel (with the first object in the Object panel rendered first, and the second one rendered second, and so forth). You can sort your Face Mask in this way to choose which Face Mask you want to be on top of the other.

Pro tip 2: You can also use other Render Targets instead of the Device Camera Texture if you’d like the Face Mask to render not the raw face, but faces with other effects (e.g. a camera renders Face Retouch to a different Render Target, which is then used to feed into the Face Mask).