JSFiddle - React, Tailwind, and code Playground

HTML

<table>
<tbody>
<tr>
    <td>
        <input type="hidden" name="MatchId[]" value="">
        <select name="TeamId[]">
            <optgroup label="Women">
                <option value="18">Women 1</option>
                <option value="17">Women 2</option>
            </optgroup>
            <optgroup label="Men">
                <option value="9">Men 1</option>
                <option value="8">Men 2</option>
            </optgroup>
        </select>
    </td>
    <td>
        <select name="Day[]">
            <!-- blah -->
        </select>
    </td>
    <td>
        <input class="addButton" type="button" value="+">
    </td>
    <td>
        <input class="removeButton" type="button" value="-">
    </td>
</tr>
</tbody>
</table>

JavaScript

$('.addButton').live('click', function()
{
    var $btn = $(this);
    var $row = $btn.closest('tr')

    var $clonedRow = $row.clone();
    $clonedRow.find("select").each(function(i){
        this.selectedIndex = $row.find("select")[i].selectedIndex;
    })

    $btn.closest('tbody').append( $clonedRow );
});