Complete a datetimepicker with the data of another

I have 2 datepicker:

.

The first one shows a date when a record was entered In the second the date of edition is shown How can I make the second datepicker show the same value as the first one by default and also change the data of the first datepicker the second one changes?

This is my script

<script>
$('.fecha').datepicker({
    dateFormat: 'dd-mm-yy',
    changeMonth: true,
    changeYear: true
});

$(document).ready(function(){
    $('.tiempo').mdtimepicker();
});