Summary
In an order where we have two identical items, and one of the items is returned, the rates for both items are displayed in the UI, rather than just the rates for the item that was returned being displayed in the UI. This information on fees is for information only, as what will actually be returned is what is filled in on the Return Note.
Simulation
To simulate this scenario, it will be necessary to place an order with two equal Items (SKU), we will see that in the order, the rates for the two items will be added and displayed in the UI. However, when returning only one of the items, we will see that the return referring to the total of fees will be displayed in the UI, instead of showing the fees referring to only one item.
Workaround
We don't have a workaround for this case.