No mention of what the second child did or said. This is almost word-for-word the Child 1 (The Eleventh Hour) page.
A patient in the Royal Leadworth Hospital had two children. She was in a coma so that meant Prisoner Zero could use her as a disguise. As the patient was dreaming of her children they appeared in the disguise too. However, this disguise soon failed when Amy Pond noticed the first child was speaking through her mother's mouth. The three chased Amy and Rory Williams through the hospital but changed form into Amy dreaming of the Eleventh Doctor. (TV: The Eleventh Hour)