Edited Unassigned: An item with the same key has already been added [15120]

I upgraded 4.0.1 v. but I have an error.
Exception : An item with the same key has already been added

```
//GC.Collect();
var excelPath = new FileInfo(epath);
ExcelPackage pck = new ExcelPackage(excelPath);

ExcelWorksheet ws = pck.Workbook.Worksheets["vt"];

__>>This>>__ ExcelWorksheet wPvt = pck.Workbook.Worksheets.Add("pvtSheet");
var pvSh = wPvt.PivotTables.Add(wPvt.Cells["B5"], ws.Cells[ws.Dimension.Address.ToString()], "pvtS");

pvSb.Compact = true;
pvSb.CompactData = true;

pvSb.RowFields.Add(pvSb.Fields[7]);
pvSb.RowFields.Add(pvSb.Fields[12]);
pt.DataFields.Add(pt.Fields[13]).Format = "#,##0";
pt.DataFields.Add(pt.Fields[17]).Format = "#,##0";
pt.DataFields.Add(pt.Fields[18]).Format = "#,##0";
pt.DataFields.Add(pt.Fields[19]).Format = "#,##0";
pt.DataFields.Add(pt.Fields[20]).Format = "#,##0";
pt.DataFields.Add(pt.Fields[25]).Format = "#,##0";
pt.DataFields.Add(pt.Fields[21]).Format = "#,##0";
pt.DataFields.Add(pt.Fields[22]).Format = "#,##0";
pt.DataFields.Add(pt.Fields[23]).Format = "#,##0";

pt.DataOnRows = false;
pt.ShowDrill = false;

pck.Save();
pck.Dispose();
```