Answer:
To present two approaches that allow the reader to have a broader view of the narrative.
Step-by-step explanation:
The narrator of a story is the voice that tells the facts, the situations, the events and can even show the thoughts, emotions and sensations of the characters. In other words, the narrator is the storyteller and it is the narrator's approach that delimits the level of depth to which the reader will be submitted.
The use of two narrators in the story expands the reader's approach and perception of the narrative. This technique allows the reader to have access to two different views of the same story, giving more details and extending the reader's understanding.