Significance of Uniqueness within model and inventory items

Description - We have two orgs:

1. DC (Serial number uniqueness - Unique within Model and Inventory Item), serial controlled at Sales order issue.
2. DRP (Serial number uniqueness - Unique within Model and Inventory Item), serial controlled at Receipt.

We have model items, From model items we create configured item and that we ship on SO.

Shipment of SO occurred from DC with Item A1 with SN1 serial number. When we go to manage serial number UI, querying the SN1, seeing status is issued out of store. in the DRP org we are trying to complete an another item A2 via WO, upon WO completion, when we are entering same serial number SN1, system is throwing an error "serial number uniqueness violated".