well in the brain is composed off many parts for example the cortex , thalamus, hypothalamus etc.. the most important parts of the brain are in the center the cortex is only used for thinking and a few other things and it is the hypothalamus that regulates breathing, heartbeat and other vital functions. while if you remove half of the cortex the other half would be responsible and take over the other halfs functions. the result would most likely be the same if the boy had a heathy brain although removing half of it for no reason would not be advisable.also removing part of a clones brain wouldnt make much of a difference first off you couldnt attach the brain without a very lucky stem cell transplant and still the neurons wouldnt work very well as brain connections grow over time so it would be pointless to transplant. and no a person can not be in two places at one unless they were siamese twins with a conjoined brain but thats probably not what you mean by your last question.
Hope this helped you GreenDestiny