Watching the girl with the split tongue reminded me of the girl who can write in different languages with both hands at the same time. President Garfield could write with both hands at the same time one in Latin the other Greek. I still have trouble writing in one.
I wrote in a previous post
However in life there are many tasks that need both hands to do complex tasks such as typing this sentence. Both hands and fingers coordinate almost without thought and the more I think the more I mistype. It would seem to me both sides of the brain have knowledge of the words being typed otherwise they would not be able to coordinate the movements. Each side of the brain must be coordinating based on it's understanding of the task.
Thinking about this some more suggests to me that the hemispheres of my brain work in parallel to accomplish the task at hand. If it is easier and more convenient for both to cooperate with one side dominant and the the other side subordinate then it can be done that way. For my learning of most tasks that makes more sense but if needed and the tasks requires differentiation it also can be done. However once habituated the task becomes very hard to unlearn.