Picking up on the idea of @Halfthawed of a torso- or stomach-mounted face/head I could imagine a post-modern species, the enteric nervous system of which was forced to improve upon its means of communicating with the brain in order to prevent self-poisoning during situations of increased social pressure.
The formerly single-headed species would suffer huge death counts due to people ignoring their revolting stomachs and binging themselves to death, poisoning themselves with intolerable amounts of sugar or alcohol or destroying their livers, kidneys and cardiovascular systems in the long term. Maybe the only available food they needed to sustain themselves was also toxic to them and they needed to very carefully avoid poisoning themselves.
Maybe they reach maturity quite late in life and fall victim to those longterm effects before getting the opportunity to procreate.
Over extended time periods, only those whose gut-brains were smart and aware enough to pursue or trick their head-brains into abstaining from those excesses, would reach maturity and pass on their tendency for developing smarter and more self-aware gut-brains.
After a while, a state was reached, where some peoples unusually smart guts where sufficiently self-aware to project complex imagery into their bodies' master brain, but a large portion of those cases failed due to the master brains being hospitalized as hallucinating or just dying because of their gut-brains committing suicide (shutting down digestive functions) out of frustration. After all their limited means of communicating their problems did not suffice to reach the ones in charge.
Only the most devoted, intelligent and persistent gut-brains managed to carry their bodies to survival and an arms race began between head- and gut-brains. While the head-brains optimized their ability in dealing with that alien entity inside their bodies, the likes of which they had never -- in their evolutionary history -- encountered, those gut-brains became more successful, who appeared less alien to their head-brains.
By chance, the gut brains adapted faster and developed facial features and means of vocal communication which enabled them to communicate with their head-brains in the way they were used to. They also developed means of visually perceiving the environment so they could more easily relate to their head-brains impression of the world.
Nowadays most members of society are either gut- or head-brain of a shared body and in most cases, they cooperate in deciding upon food-intake and matters of bodily-health.