User names do NOT have to be unique. Bill, Sam. Will, William, Carol, Kathy, Karen, Debbie are pretty common user names. There are three people in my apartment complex whose real life first name really is Carol.70 to 60 years ago Kathy, Cathy, Katherine, Catherine Carol, Carolyn, Deborah and Debbie were all popular first names. I I had neighbor who was year younger than me whose first name was also Carol. She died from lung cancer more than 10 years ago. according to long time neighbor than 10 years ago..
User names / Yahoo nicknames DO NOT have to be unique.