A company’s platform has reported multiple instances of duplicate orders in its order-processing system.

The NumberOfDeduplicatedSentMessages metric counts messages that Amazon SQS accepts but does not add to a FIFO queue because they have already been identified as duplicates within the deduplication interval. A high or unexpected value indicates that producers are repeatedly sending messages with the same message-deduplication ID or identical content when content-based deduplication is enabled. This directly helps determine whether duplicate submission attempts originate from message producers. ApproximateNumberOfMessagesVisible shows messages currently available for retrieval and is useful for identifying queue backlogs. ApproximateNumberOfGroupsWithInflightMessages measures the number of active FIFO message groups and helps evaluate concurrency. NumberOfMessagesSent reports messages added to the queue but does not specifically identify duplicate send attempts. Therefore, NumberOfDeduplicatedSentMessages provides the most relevant diagnostic evidence.

================