JSFiddle - React, Tailwind, and code Playground

HTML

<div style="border:1px solid blue; cursor:pointer; width:100px; text-align:center; position:absolute" onclick=clone()>Клонировать</div>
<div class="name_container" style="border:1px solid blue; width:200px; height:100px; text-align:center; position:absolute; margin-left:110px " class="part_01"></div>

JavaScript

var div_block = document.createElement('div');
div_block.className = 'BOX';
div_block.style.border = '1px solid red';
div_block.style.cursor = 'default';
div_block.innerHTML = 'Леонардо'
div_block.setAttribute('onmouseover', "this.style.backgroundColor = 'green'");
div_block.setAttribute('onmouseout', "this.style.backgroundColor = ''");
document.getElementsByClassName('name_container')[0].appendChild(div_block)

function clone(){
var clone_div = document.getElementsByClassName('BOX')[0].cloneNode(true)
document.getElementsByClassName('name_container')[0].appendChild(clone_div)
}