SAP Message XT023 - System &1 already registered in domain

Diagnosis
A system &V1& is already registered in the domain controller ofthe transport domain &V2&. Two systems with the same systemnames cannot be administered in one domain.

System Response
You cannot include the system in domain &V2&.

Procedure
Use transaction STMS to display the systems which are alreadyregistered (STMS -> Overview -> Systems) at the domain controller.Delete system &V1& from the transport domain and repeat thelogon in system &V1& if you want to register the new system&V1& in the transport domain &V2&.