yes it is normal for people with and without mental disorders to have automatic thoughts\conversations\daydreams. there are many different classes, therapies and other techniques that center around controlling these automatic thoughts, conversations and daydreaming. some of those are called grounding, mindfulness, breathing, relaxation, yoga, there are even religions that teach oneself how to control their automatic thoughts/conversations\daydreams like Buddhism.

some countries have a non dissociative disorder called maladaptive daydreaming disorder that covers having excessive automatic thoughts, conversations /daydreaming. if you think you are having this kind of problem to the abnormal levels there are tests and medication for it.

as for dissociative type where its the alters doing the talking, thinking daydreaming and another alter or host is aware of it, its called being co conscious, and yes it is normal for this to happen. its part of the healing process for some that the amount of co consciousness increases with healing. its usually a good thing and a huge step forwards on the healing process towards everyone being able to communicate, work together and become one.