将第二个折线图添加到FLOT图表

I loading value from mysql database, 64000005E5CBCD28 it is value of temperature from sensor

$dataset1[] = [(1000*strtotime($row['DATETIME'])),$row['64000005E5CBCD28']];

thereafter

var dataset1 = <?php echo json_encode($dataset1); ?>;

and this command make chart, for one line, my code works well.

$.plot($("#placeholder"), [ dataset1 ], options);

So, how to add next line chart, like a dataset2-second sensor? My try, multiply everything not work.

$dataset2[] = [(1000*strtotime($row['DATETIME'])),$row['57852725725779']];
var dataset2 = <?php echo json_encode($dataset2); ?>;
$.plot($("#placeholder"), [ dataset2 ], options);