Seaquel
SQL Server error code

SQL Server error 5318

SQL Server raises error 5318 at severity 16, which marks a problem with the query or data that you can correct.

In a MERGE statement, the source and target cannot have the same name or alias. Use different aliases for the source and target to ensure that they have unique names in the MERGE statement.
Msg5318
Severity16
Group5000–5999

Source: Database Engine events and errors