Our ancestors often used the following naming procedure when picking out a name for a new child. This explains why certain names are VERY common in a given family line. Watching for these patterns can help in your genealogy research.
1st son = father's father
2nd son = mother's father
3rd son = father
4th son = father's oldest brother
5h son = father's 2nd oldest brother or mother's oldest brother
1st dau = mother's mother
2nd dau = father's mother
3rd dau = mother
4th dau = mother's oldest sister
5th dau = mother's 2nd oldest sister or father's oldest sister
Keep in mind that some families named their children by this method and if the child died young, they named the next child the same name. So, it may be possible to have duplicate named children in a family.