JSFiddle - React, Tailwind, and code Playground
HTML
<form method="post" id="customForm2" action="">
<div class = "linguas" id="input_1" style="margin-bottom: 10px;">
<select>
<option value="volvo">default</option>
<option selected="selected" value="saab">Saab</option>
<option value="mercedes">Mercedes</option>
<option value="audi">Audi</option>
</select>
</div>
</form>
<div id="copiar">
<button class="button" href="#" id="btnAdd1">
<span class="icon icon3">add</span>
</div>
JavaScript
$('#btnAdd1').click(function (event) {
var num = $('.linguas').length;
var newNum = new Number(num + 1);
var newElem = $('#input_' + num).clone(false).prop('id', 'input_' + newNum);
newElem.children(':text').val('');
$('#input_' + num).after(newElem).find('#input_' + num +'> option:selected').removeAttr("selected");
$('#btnDel1').prop('disabled', '');
if (newNum == 4) $('#btnAdd1').prop('disabled', 'disabled');
});