I only had one, my Mom's father. I called him Papa.

Nanna and Poppa for both sides when with them. Talking about them, it was Nanna (Their name) and Poppa (Their name).

Grandma and granddad same for both sides of the family but like yourself I only had one granddad my dad's dad had diеd before I was born..

I seem to remember my grandma on my dad's side would be referred to as grandma followed by the family surname if there was ever any reason to specify which grandma it was.
乂º‿º乂

I called all of them Grandma and Grandpa, and GREAT Grandma and Great Grandpa. I actually met and knew a couple of my "Greats". It's an American Midwestern thing.

The two grandfathers were "Granddaddy" and "Grandpa"

On dads side, grandpa and grandma; moms side papa and mummo

Grammy and Grampy

grandma and grandpa i was only close to my dad's side of the family tho my mom's side were snobs

Gramps and Gma

My mother's mother was grandma last name, my dad's father was just grandpa. Unfortunately i never had any relationship with them.

Dads side: Grandma and Grandpa

Mom's side: Grandmother and Grandfather

Dad's side was "Grandma [her last name]". My dad's father died before I was born so I didn't call him anything.

Mom's side were just "Grandma and Grandpa".

My grandfather died when I was 3 so I didn't really get to call him anything I just remember staring at him a lot. But I called my grandma "Mommy"

Almost forgot. My great grandma was alive when we first arrived at my grandma's house... Her Name was Lola but we were too little to pronounce it properly so we called her "LoLo."