I just think of Ava Gardner.....
One of my grandmothers, of blessed memory, was named Eva. Just my luck when my husband and I have a daughter, (who we plan to name either Eva or Ava in her memory) we'll be accused of being trendy (b/c of either Eva Longoria or Reese Witherspoon's daughter).
People forget that names cycle and recycle. Chances are if Eva was a popular name 60-5 years ago, I'm not the only person w/ a grandmother or great-grandmother with the same name. If I'm not the only person with an ancestor with that name, I'm probably not the only person on earth who would like to honor that relative by naming my child after her. It could be the same thing with some of these celebrities as well. It might be a case of copying for the sake of copying after all.