SOBJ object &1 has already been used

What causes this issue?

SOBJ objects cannot be used more than once in the Transport Tool, as
the object network of the tool needs to be reconstructed uniquely from
the transport request.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.