Question:   Why the system enforces the uniqueness per Product rule and will not base the uniqueness on SN that exist in the Qty at that time.

Answer:   The inventory Handling will enforce the uniqueness rule that has been assigned for Serial Number tracking within the System setup.  There was an request to have the Serial Numbers unique within just the Qty on hand at that time, so user could bring already used SN back into the stock through inventory handling.  We cannot permit users to assign serial numbers that have once been used to new receipts over and over again. To do so would negate the uniqueness of the serial numbers. If we did so, then we would be faced with a problem when a serial number returns to inventory.  If a customer sends back a serial number, both the customer and our user will probably want to know the history of that particular serial number. How would they know which one it was if we allowed new receipt records to be assigned Serial numbers already once used within the system?  So, no, we cannot allow serial numbers based on whether or not they are in inventory at the moment. Another situation could happen when they added a duplicate serial number to material on hand, then needed to receive the original back into stock for some reason. Then we would have to have two serial numbers exactly the same for the same product, which obviously, we cannot do.

Possible Resolution:  We recognize that the return of one Serialized item back into inventory might be needed.  We are reviewing the code within the Inventory Handling Receiving module, and looking to have any option to pick from already used Serial Numbers if the customer whats to bring it back in.  This way we will actually be maintaining the history of this Serial number by requiring the users to select the record that already exists within the system.  So we will not be createing a new Serial Number record, that could lead to duplicated information within the system, but rather requiring the users to select that information from pre-existing serial number records.