modExtenciones.ReadExcelFile valida clumnas repetidas

App_Code/modExtensiones.vb

@@ -177,6 +177,52 @@ Namespace Extensiones
             Dim dataTable As DataTable = New DataTable()
             Dim worksheet As GemBox.Spreadsheet.ExcelWorksheet = excelFile.Worksheets(0)
 
+
+
+            ' VALIDACIÓN DE COLUMNAS DUPLICADAS
+            Try
+                If firstRowHasHeaders Then
+                    Dim columnNames As New List(Of String)()
+
+                    For col As Integer = 0 To worksheet.Rows(curRow).AllocatedCells.Count - 1
+                        Dim cellValue As Object = worksheet.Rows(curRow).Cells(col).Value
+                        Dim colName As String = If(cellValue Is Nothing, $"Unnamed Column {col + 1}",
+                                           cellValue.ToString())
+
+                        columnNames.Add(colName)
+                    Next
+
+
+                    Dim duplicates As New List(Of String)()
+                    Dim dict As New Dictionary(Of String, Integer)(StringComparer.OrdinalIgnoreCase)
+
+                    For Each name In columnNames
+                        If dict.ContainsKey(name) Then
+                            dict(name) += 1
+                        Else
+                            dict(name) = 1
+                        End If
+                    Next
+
+                    For Each kvp In dict
+                        If kvp.Value > 1 Then
+                            duplicates.Add(kvp.Key)
+                        End If
+                    Next
+
+
+                    If duplicates.Count > 0 Then
+                        Alert(New Object, "El archivo de Excel contiene columnas duplicadas, las columnas duplicadas son: " & String.Join(", ", duplicates), TipoMensaje.MsgAdvertencia)
+                        Return New DataTable
+                    End If
+                End If
+            Catch ex As Exception
+
+            End Try
+            ' FIN DE LA VALIDACIÓN
+
+
+
             For cols = 0 To worksheet.Rows(curRow).AllocatedCells.Count - 1
 
                 If firstRowHasHeaders Then