Based on the information your 16 months identical twins have a ridge or a boney prominence from their anterior fontanel to the hairline, and shows tantrums and fear to interacts with stranger, more over bang heads at night and want to know if it was normal.
It is pretty normal for that age kids to behave in such fashion. Nothing to worry as long as the developmental milestones are achieved (for more information about milestone you may ask your pediatrician
Thanks. Hope it helps.