Edit in JSFiddle

var countries = 'US,Germany,UK,Japan,Italy,Greece'.split(','),
    data = [];

for (var i = 0; i < 5; i++) {
    data.push({
        id: i + 1,
        country: countries[i % countries.length],
        date: new Date(2014, i % 12, i % 28),
        amount: Math.random() * 10000,
        active: i % 4 == 0
    });
}
var cv = new wijmo.collections.CollectionView(data);

var multiRow = new wijmo.grid.multirow.MultiRow('#multiRow');
multiRow.itemsSource = cv;
multiRow.layoutDefinition = [
    {
        colspan: 1, cells: [
          { binding: 'id' },
          { binding: 'country', isReadOnly: true }
        ]
    },
    {
        colspan: 2, cells: [
          { header: 'date1', binding: 'date', format: 'dd-MM-yyyy' },
          { header: 'amount1', binding: 'amount', format: 'n3' },
          { header: 'date2', binding: 'date', format: 'dd-MM-yyyy' },
          { header: 'amount2', binding: 'amount', format: 'n3' }
        ]
    },
    {
        colspan: 1, cells: [
          { binding: 'active' }
        ]
    },
];

function btn_click1(e, args) {
    wijmo.grid.xlsx.FlexGridXlsxConverter.save(multiRow, { }, 'MultiRow.xlsx');
}

<input type="button" onclick="btn_click1()" value="Export" /><br>
<div id="multiRow"></div>