cron jobs are over lapping

We have scheduled cron job at morning 8am and afternoon 12 pm but the afternoon job ran with morning.

Below is the code which I'm using issue is overnight job ran on time and ran with morning .

function hook_modulename_cronapi()
{
$items = array();
/* Client Daily report Start here*/
$items['test_overnight'] = array(
'title' => t('Overnight Report 8-AM'),
'file' => 'overnight.jobs.inc',
'file path' => drupal_get_path('module', 'test_modules') . '/cron',
'callback' => 'overnight_report',
'callback arguments' => array(),
'enabled' => TRUE,
'scheduler' => array(
'name' => 'crontab',
'crontab' => array(
'rules' => array('2 8 * * *'),
),
),
'launcher' => array(
'name' => 'serial',
'serial' => array(
'thread' => 'any',
),
),
);

$items['test_morning'] = array(
'title' => t('Morning Report 8AM-noon'),
'file' => 'morning.jobs.inc',
'file path' => drupal_get_path('module', 'test_modules') . '/cron',
'callback' => 'morning_report',
'callback arguments' =>array(),
'enabled' => TRUE,
'scheduler' => array(
'name' => 'crontab',
'crontab' => array(
'rules' => array('5 12 * * *'),
),
),
'launcher' => array(
'name' => 'serial',
'serial' => array(
'thread' => 'any',
),
),
);

return $items ;
}

Please suggest solution for this very important for us please help us.

Thanks in advance.