Workbook workbook = ImportWorkbook( originalFileName );
ExportWorkbook( workbook, destinationFileName );

        private Workbook ImportWorkbook( string  fileName )
        {
            Telerik.Windows.Documents.Spreadsheet.Model.Workbook workbook;
            IWorkbookFormatProvider formatProvider = new Telerik.Windows.Documents.Spreadsheet.FormatProviders.OpenXml.Xlsm.XlsmFormatProvider();

            using( Stream input = new FileStream( fileName, FileMode.Open ) )
            {
                workbook = formatProvider.Import( input );
            }
            
            return workbook;
        }

        private void ExportWorkbook( Workbook workbook, string fileName )
        {
            Telerik.Windows.Documents.Spreadsheet.FormatProviders.IWorkbookFormatProvider formatProvider = new Telerik.Windows.Documents.Spreadsheet.FormatProviders.OpenXml.Xlsm.XlsmFormatProvider();

            using( Stream output = new FileStream( fileName, FileMode.Create ) )
            {
                formatProvider.Export( workbook, output );
            }
        }