two different postback documents for the same USPS shipment

When we post-in an order and ship it by USPS we get two different XML documents back. The first one has the Tracking Number and the second one doesn't.

I attached files of the first and second postback documents. I masked account numbers, etc.

Are they supposed to be different? What is the purpose of each document?

NOTE: When we ship with FIMS2, we get two documents that are almost the same. These are two differences between the documents are the <ReadyTimeType> and <EMail> in the Address of ShipperAddress

Thanks.

Attached Files

• first_postback.xml.txt (6.1 KB)
• second_postback.xml.txt (5.6 KB)