If I get it correctly, You need to wrap them in an array and pass to Javascript.
function get_ldap_attr() {
header("Content-type: application/json");
...
// suppose you want to return $second_var
echo json_encode(array($sup,$second_var));
die();
}
Success function of JSON request will receive them as array. You can access them with integer index.
jQuery(function() {
jQuery('#empLanId').on('blur', function() {
var lan = jQuery('#empLanId').val();
var ajaxurl="<?php echo admin_url("admin-ajax.php", null); ?>";
var data = { action: "get_ldap", lan: lan};
jQuery.ajax({
type: 'POST',
url: ajaxurl,
data: data,
dataType: 'json',
success: function(response) {
response[0] // first $sup variable
response[1] // second $second_var variable
//jQuery('#empSupLanId').val(response.lanid);
//jQuery('#empSupName').val(response.fullname);
//jQuery('#empSupNumber').val(response.phone);
}
});
});
});