My grandkids and step-grandkids have so many grandparents, most of whom see them regularly, so its a confusing mess. I am called Grandma "Brown" by most of the kids, but my DH's ex-wife from 30 years ago decided to take his last name back, even though she had been married and divorced since. So she, being the grandkids "blood" grandma, took the name Grandma "Brown". So I have to be called something else that doesn't flow well. Irritated? Not much.
Funny, with so many blended families and non-traditional arrangements. We can get in the sad game of trying to "Out-Grandma" each other if we have a competitive streak, can't we?