I have two tables with identical fields, as below.

Table1

      | EmployeeNIN     |    KeySection   | Result | Comment | Auditor |
      |:--------------: |:---------------:|:------:|:-------:|:-------:|
      |CF60012102UJDJ   | Vote Name       |  UBOS  | Great   |  UZ062  |
      |CF60012102UJDJ   | Employee Number | 78562  | Nice    |  UZ062  |
      |CF60012102UJDJ   | Supplier Number | 12556  | Wrong   |  UZ062  |

Table2

      | EmployeeNIN     |    KeySection   | Result | Comment | Auditor |
      |:--------------: |:---------------:|:------:|:-------:|:-------:|
      |CF60012102UJDJ   | Vote Name       |  DELL  | Great   |  UZ062  |
      |CF60012102UJDJ   | Employee Number | 78562  | Error   |  UZ062  |
      |CF60012102UJDJ   | Supplier Number | 222222 | Correct |  UZ062  |

The main task is to run through table1 and see any changes to the Result field and update table2 . i have been using EmployeeNIN as a target and source identifier but got error messages as below.

The MERGE statement attempted to UPDATE or DELETE the same row more than once. …

below is my merge statement ..

     MERGE [dbo].[Tabel2] AS t  
     USING (  
         SELECT * FROM  Tabel2  
     ) AS s ON    t.EmployeeNIN = s.EmployeeNIN  AND t.[KeySection] = s.[KeySection]  
     WHEN MATCHED THEN  
         UPDATE SET  

             t.[Result]        =  s.[Result]
            ,t.[Comment]       =  s.[Comment] 
         
     WHEN NOT MATCHED THEN  
         INSERT (  
         [EmployeeNIN]
        ,[KeySection]
        ,[Result]
        ,[Comment]
        ,[Auditor]  
         )  
         VALUES (  
         s.[EmployeeNIN]
        ,s.[KeySection]
        ,s.[Result]
        ,s.[Comment]
        ,s.[Auditor] 
         );