If an end-user's WhatsApp account is associated with multiple devices, those devices may support different messaging features. If one device supports your outbound message's features, but another does not, you may receive multiple delivery receipts that report contradictory delivery statuses.
For example, it is possible for WhatsApp end-users to connect their WhatsApp account to a Meta Portal. If you send a message to an end-user, and the end-user has connected their WhatsApp account to their Portal, the message may be routed to both a smartphone and a Portal. If the message includes features that are supported on a smartphone, but not a Portal, you may get two contradictory delivery receipts: one that reports that the message was successfully delivered (to the smartphone), and another that reports that the message delivery failed (to the Portal).