Very odd! I don't know about having more than one tooth in a single root, but I have read articles about people who inherently have more than the normal two sets of teeth. Do you have this in your family? Check the link below to read some of the stories of people with 3 or more sets of teeth in their lifetime. Perhaps your child also has the possibility of more than two sets of teeth and the multiples pulled from the one root are proof. I haven't read anything about a particular name for this condition. Did you ask your dentist?
I do think a person can have more than one tooth in a single root, but i am not sure about 7
to me yes i think its possible to grow more than 1 toth in the spot because i have doble tooth in my mouth but they will fal out