jquery ui datepicker setDate bug

Show how calling setDate on a none-focused datepicker change context of an open datepicker

HTML

<script src="http://code.jquery.com/ui/1.10.3/jquery-ui.js"></script>
<link rel="stylesheet" href="http://code.jquery.com/ui/1.10.3/themes/smoothness/jquery-ui.css">
<div>
    <p>
        focusing the first date field and selecting a date in the calendar then display will always result in changing the second input, due to the "beforeShow" function provided.
    </p>
    <input type="text" id="date_1" class="date-field"/>
    <input type="text" id="date_2" class="date-field"/>
</div>

JavaScript

$(".date-field").datepicker({defaultDate: '2018-11-07'});