This thangka, at first glance, looks like Chakrasambvara and Vajravahari.  But it is not.  Actually, these are Bon Deities and this is a Bonpo Painting.  For more about Bon Tradition, one of the five Tibetan traditions check out Ligmincha.org. Note the headless human in the conch shell.  Not completely headless you say?  Maybe this is better.  No thinking brain but reptilian brain intact?  We don't know.  Probably just symbolic.