Incorrect Item Quantity Distribution in Multi-Package Orders

[DarkSwoop]

Severity: Critical -> Can't ship order in production.

Summary:
When creating multiple packages for an order with multiple quantities of a single line item, the system incorrectly distributes and updates item quantities across packages.

Steps to Reproduce:

1. Create a new label for an order with one line item and a quantity of three.
2. Package the order using the default box.
3. Reduce the quantity of the item in the first package to one.
4. Add a new package.
5. Click on "Edit Items" for the second package.
6. Add the remaining quantity (two) of the line item to the second package.

Expected Result:

• Package 1 should contain one line item with a quantity of one.
• Package 2 should contain one line item with a quantity of two.
• Changes to item quantities in one package should not affect the other package.

Actual Result:

• Both Package 1 and Package 2 list the same item with two line items.
• Package 1 shows quantity one for the first line item and quantity two for the second line item.
• Package 2 shows the same distribution as Package 1.
• Changes to the quantity of the last line item update both packages simultaneously.

System Information:

• Browser: Firefox Developer Edition (129)
• Operating System: macOS
• Application Version: 2024.2.12

Additional Notes:
This bug significantly impacts the ability to accurately distribute items across multiple packages, potentially leading to shipping errors and inventory discrepancies.