We have two Fedex trackings with duplicated records. Amazon considered them invalid tracking and counted against our performance matrix.

Here is what the representative told me

"As per my understanding, you would like to verify the tracking information for multiple orders.

Our system is unable to use duplicate tracking to track the order for the buyer.

If we are unable to inform to buyer of the tracking status, the order tracking information is invalid. "

To me, the answer is that because our programmers don't want to resolve bugs, it is seller's fault.