The duplicates are not removed as the final data table is a combination of string value and integer values. If I change the entire column values as integer means I can easily remove the duplicates.
Try this way:
=> Use For Each row in DataTable to iterate through the merged datatable variable FilterDT.
=> Inside the loop use Assign activity and give below syntax: CurrentRow("RowNumber") = Decimal.Parse(CurrentRow.Item("RowNumber").ToString)
=> Outside the loop use the below condition in Assign activity: FilterDT = FilterDT.DefaultView.ToTable(True, "Date","RowNumber")
=> Write Range Workbook FilterDT back to excel.