Susan, who loves to read and write, competes against her cousin (and former best friend) in the school contest.
Author Nguyen too shares a love of writing with her own cousin.
"My cousin and I play this game where we write stories about whatever pops into our heads and then we compare them and critique them," she said.
In "Double Identity," Susan struggles to find enough motivation and confidence to write her story, until she gets some encouragement from some familiar faces from favorite books, who visit her in a dream.
The story ends with a touching moment of maturity for Susan, when she speaks kindly about her rival at the awards ceremony for the writing contest.
Just like Susan, Nguyen, age 11, loves to read and write. She said her favorite subjects in school are reading and English.
This is only one of the many stories that she's written.
"I write a mixture of fantasy and real life, but my real-life stories turn out better," she said.
When asked if "Double Identity" was a true story from her own life, she said, "[the story] is kind of a true story, but I exaggerated a few parts."
Nguyen hopes that people will learn something from reading "Double Identity."
"The message of my story is that you can't compare yourself to anybody else because everybody is special," she said.