My ex is named Andrew, and his sister is named Amanda. It's a lovely sibset until you learn that their parents call them Andy and Mandy. ;)
I know a set of sisters named Jennifer and Jenny.
I grew up living with one of my mother's friends for a while. There were 3 kids each, so 6 total. My mother's friend had two sons named William Patrick (Jr.) and Patrick William. Her daughter was named Ashley Marie, and I was Ashley Rose. Yep. It was confusing.
I know three sisters named Brianna, Shyanna, and Dianna. Their mother's name is Anna.
I recently came across someone on facebook whose daughters' middle names were Isabelle, Corabelle, Mirabelle, and Lirabelle. I actually found that to be tasteful as they all had different first names and it tied them together without being tooooo cutesy.
My best friend's name is Shauna Kristen (same middle name as her mom) and her younger brother's name is Shawn Edward (same middle name as his dad). Everyone always assumes they're twins, but they're four years apart.
I also went to school with twin sisters named Antoinette and Anjanette.
It isn't that the names are bad but Cathie stands out like a sore thumb to me. My mom is Rebecca, she goes by Becky, and even she was like "I don't know why they didn't name her Catherine."
A good friend of mines name is Katherine Alice and goes by Katie. When she was about 14, her dad remarried to a woman who had two children name Jospeh (not sure of middle name) and Katherine Rose (who went by Kate) sooo confusing :/