how to merge rows in datatable which had same value (VB)

I have one datatable tempDT with value :

Serial_No                      testong
 ---------------------------------------
 DTSHCSN001205035919201         [ OUT ] <br/> Partner : 90000032 <br/> Date : 16 Feb 2012
 DTSHCSN001205035919201         [ IN ] <br/> Partner : 90000032 <br/> Date : 16 Feb 2012
 DTSHCSN001205035919201         [ OUT ] <br/> Partner : 80000869 <br/> Date : 31 Mar 2012
 DTSHCSN001205035919201         [ IN ] <br/> Partner : 80000869 <br/> Date : 31 Mar 2012
 

The problem is I want merge duplicate serial_no into one row which the value of testong adding to new column.

I have tried many ways, but I can't find the solution.

Here is my code behind :

    Dim tempDt = GetItemDataTable()
     Dim dtData As New DataTable
 
     dtData.Columns.Add("Serial_No")
     Dim i As Integer = 0
     Dim row As DataRow
 
     For Each row In tempDt.Rows
         i += 1
         Dim dr As DataRow = dtData.NewRow
         dr("Serial_No") = row(0)
         If dr("Serial_No") = row(0) Then
             Dim colBaru As GridViewDataTextColumn = New GridViewDataTextColumn()
             colBaru.Caption = i
             colBaru.FieldName = i
             colBaru.CellStyle.HorizontalAlign = HorizontalAlign.Center
             colBaru.HeaderStyle.HorizontalAlign = HorizontalAlign.Center
             colBaru.Width = 150
 
             colBaru.UnboundType = DevExpress.Data.UnboundColumnType.Integer
             colBaru.VisibleIndex = grid.VisibleColumns.Count
             colBaru.PropertiesTextEdit.DisplayFormatString = "d1"
             colBaru.PropertiesTextEdit.EncodeHtml = True
             grid.Columns.Add(colBaru)
             dtData.Columns.Add(i)
             dr(i) = row(3)
             dtData.Rows.Add(dr)
 
         Else
             dr("Serial_No") = row(0)
             dtData.Rows.Add(dr)
         End If
 

When I debug the result is :

But I wanted the result is like this :

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