Item &1 is an alternative to item &2 and will not be copied

What causes this issue?

You cannot use the copy function to transfer alternative items from a
reference document into the target document.

System Response

The system simply copies the original item into the target document
when the message is confirmed.

How to fix this error?

If you want to copy the alternative item rather than the original item
into the target document, use the selection list rather than the copy
function.

Error message extract from SAP system. Copyright SAP SE.