old_contents: import React from 'react';
  import Td from './Td';
  
  const TableRow = ({ columns, row, totals }) => (
    <tr>
      {
        columns.map(c => <Td
          key={row[c.property] || `empty-${c.property}`}
          cell={row[c.property]}
          row={row}
          alignment={c.align}
          format={totals ? c.formatTotal || c.format : c.format}
        />)
      }
    </tr>
  );
  
  TableRow.propTypes = {
    columns: React.PropTypes.arrayOf(React.PropTypes.object).isRequired,
    row: React.PropTypes.object.isRequired,
    totals: React.PropTypes.bool
  };
  
  export default TableRow;
  
new_contents: import React from 'react';
  import Td from './Td';
  
  const TableRow = ({ columns, row, totals }) => (
    <tr>
      {
        columns.map((c, i) => <Td
          key={`${i}-${row[c.property]}` || `${i}-empty-${c.property}`}
          cell={row[c.property]}
          row={row}
          alignment={c.align}
          format={totals ? c.formatTotal || c.format : c.format}
        />)
      }
    </tr>
  );
  
  TableRow.propTypes = {
    columns: React.PropTypes.arrayOf(React.PropTypes.object).isRequired,
    row: React.PropTypes.object.isRequired,
    totals: React.PropTypes.bool
  };
  
  export default TableRow;
  
subject: fix duplicate keys in columns when using the same property in multiple columns