title: An item with the same key has already been added. SSRS Report Builder
body: <p>i know that there are already some forums on here, but can someone help me identify the duplicates and how to alias the column names? I believe the left joins at the bottom are creating this error in report builder.    </p>
  
  <pre><code>SELECT  CASE A.DTASERIES
        WHEN 2 THEN 'Financial'
        WHEN 3 THEN 'Sales'
        WHEN 4 THEN 'Purchasing'
        WHEN 5 THEN 'Inventory'
        WHEN 6 THEN 'Payroll – USA'
        WHEN 7 THEN 'Project'
        ELSE ''
      END AS DTA_Series ,
      JRNENTRY AS JournalEntry,
      D.ACTNUMST AS AccountNumber,
      C.ACTDESCR AS AccountDescription,
      A.GROUPID AS DTA_GroupID,
      CODEID AS DTA_CodeID,
      GROUPAMT ,
      CASE 
      WHEN CODEAMT &gt; 0 THEN CODEAMT
      ELSE 0 
      END AS Debit,
      CASE 
      WHEN CODEAMT &lt; 0 THEN CODEAMT
      ELSE 0 
      END AS Credit,
      A.TRXDATE  AS TransactionDate,
      A.DTAREF AS DTA_Reference,
  
      DTA_GL_Reference ,
      A.DOCNUMBR AS OriginalDocumentNumber ,
      A.RMDTYPAL ,
      CASE PSTGSTUS
        WHEN 1 THEN 'Unposted'
        WHEN 2 THEN 'Posted'
        ELSE ''
      END AS DTA_PostingStatus ,
      B.DOCNUMBR ,
      B.RMDTYPAL ,
      POSTDESC AS PostingDescription,
      DTAQNTY 
      FROM    dbo.DTA10100 AS A
      LEFT OUTER JOIN dbo.DTA10200 AS B ON A.ACTINDX = B.ACTINDX
                                           AND A.DOCNUMBR = B.DOCNUMBR
                                           AND A.DTAREF = B.DTAREF
                                           AND A.DTASERIES = B.DTASERIES
                                           AND A.GROUPID = B.GROUPID
                                           AND A.SEQNUMBR = B.SEQNUMBR
      LEFT OUTER JOIN dbo.GL00100 AS C ON A.ACTINDX = C.ACTINDX
      LEFT OUTER JOIN dbo.GL00105 AS D ON C.ACTINDX = D.ACTINDX
  </code></pre>