JSFiddle - React, Tailwind, and code Playground

HTML

<form id="fpf" class="" method="post" action="">
    <select name="estado" class="estado" onchange="buscar_cidades(this)">
        <option value=""></option>
        <option value="000001">AC</option>
        <option value="000002">AL</option>
        <option value="000003">AM</option>
    </select>
</form>
<form id="fpj" class="" method="post" action="">
    <select name="estado" class="estado" onchange="buscar_cidades(this)">
        <option value=""></option>
        <option value="000001">AC</option>
        <option value="000002">AL</option>
        <option value="000003">AM</option>
    </select>
</form>

JavaScript

function buscar_cidades(e) {

    var formid = e.form.id;
    var estado = e.value;
    alert(formid + ' - ' + estado);
}