Bifications in the tree can appear like it has two heads. Mostly one will appear bigger or more dominant than the other. From the ground it is difficult to see the condition of the join between them. You may see a bulge of wood growing to one or both sides just below the junction. In general both sides are trying to out grow the other in an effort to become dominant.
The healthy outward appearance can hide a problem of vital structure for the tree and safety for us on the ground. Someof these can be managed by weight reduction in accordance with Australian Standards 4373 over a period of time. If the consequence of failure is high then the tree may need to be removed.