Grandparents and Great-Grandparents can have the same last name.
So?
Sometimes when talking about my mother or mother-in-law, they’ll say “Bubby_____,” but sometimes they’ll just say “Bubby.” Nonetheless, we figure out who they’re talking about.
The Wolf
Cute story: We were spending Shabbos by my mother’s house when my oldest was very young (probably about two or three at the time). He was playing with my mother when there was a knock at the door. Naturally he ran to the other and when we opened it, it was my mother-in-law, who came over to visit.
Squealing with joy, he exclaimed “More Bubby!!!!” 🙂