<?php

	$res = array();
	$res[] = array("16/08/2013", "13:32", "ROBERTO");
	$res[] = array("16/08/2013", "13:16", "AMANDA");
	$res[] = array("14/08/2013", "12:36", "SILMARA");
	$res[] = array("14/08/2013", "", "ROBERTO");
	$res[] = array("14/08/2013", "", "KATIA");
	$res[] = array("13/10/2015", "16:47", "ROBERTO");
	$res[] = array("14/08/2013", "", "SILMARA");
	$res[] = array("14/08/2013", "", "AMANDA");

    usort( $res, 'compara' );
    print_r( $res );
    
    function compara( $a1, $a2 ) {
    	$ts1 = substr($a1[0],6,4).substr($a1[0],3,2).substr($a1[0],0,2).$a1[1];
    	$ts2 = substr($a2[0],6,4).substr($a2[0],3,2).substr($a2[0],0,2).$a2[1];
    	return strcmp($ts1, $ts2);
    }