They don't mind. I call Miss Mini: Miss Mini K., Mini Min, where's my dog?, mommas girl; princess, she answers to all of them!!!
I call Miss Mia: MiaMia and now poopyface (based on a new habit)...sadly she answers to both...
I had a dog that we rescued years ago that was a senior, she came with the name Wibbles, we called her Wibbles and/or Nellie Bell...she answered to both.