Conversation so far:
What celebrities has Oprah Winfrey interviewed?
In 1993, Oprah Winfrey hosted a rare prime-time interview with Michael Jackson.
Who else has Oprah Winfrey interviewed besides Michael Jackson?
On September 10, 2007, David Letterman made his first appearance on The Oprah Winfrey Show, as its season premiere was filmed in New York City.
When did Oprah Winfrey appear on the late show?
On December 1, 2005, Oprah Winfrey appeared on the Late Show with David Letterman to promote the new Broadway musical The Color Purple.

Question: Did she appear on his show more then once?
Self-contained rewrite: Did she appear on David Letterman's Late Show more then once?