The Collected Stories of Katherine Anne Porter is a book by Katherine Anne Porter published by Harcourt in 1965, comprising nineteen "short stories and long stories", as Porter herself would say. It won the Pulitzer Prize for Fiction and the U.S. National Book Award for Fiction.
Katherine Anne Porter is a multiple award-winning author.
The context states that her book won both the Pulitzer and the US National Book Award. Two awards constitutes multiple awards, but to know this requires knowledge of how the English language works that the model may not have.