The two words "prayer" and "request" mean basically the same thing. Together they emphasize that the people were sincere as they made their request to Yahweh. See how you translated similar words in [1 Kings 8:28](./27.md). (See: [[rc://en/ta/man/translate/figs-doublet]])
Solomon twice requests Yahweh to forgive the people. This emphasizes the earnestness of his request. (See: [[rc://en/ta/man/translate/figs-parallelism]])