bootstrap-table fliter-control 下拉框数据重复

Question

<table id="factorytable" data-pagination="true" data-page-number="1"
           data-page-size="13" data-search="true" data-filter-control="true" data-filter-show-clear="true"
           data-toggle="table"
           class="table table-hover">
        <thead>
        <tr>
            <th style="text-align: center; " data-field="id" data-filter-control="select">
                序号
            </th>
            <th style="text-align: center; " data-field="factoryname">
                厂家名称
            </th>
        </tr>
        </thead>
        <tbody>
        <tr data-index="0">
            <td style="text-align: center; ">1</td>
            <td style="text-align: center; "></td>
        </tr>
        <tr data-index="1">
            <td style="text-align: center; ">2</td>
            <td style="text-align: center; "></td>
        </tr>
        </tbody>
    </table>