Mail function is working only once at a time : Codeigniter - codeigniter

Question

I am using Codeigniter email library to send emails. I have integrated email settings like this in my model
public function savedetails($data) {
$firstmail = $this->sendmail(1, $data);
$secondmail = $this->sendmail(2, $data);
}
public function sendmail($flag, $data) {
$this->load->library('email');
$config = array(
'protocol' => 'smtp',
'smtp_host' => $this->config->item('emailhost'),
'smtp_user' => $this->config->item('emailusername'),
'smtp_pass' => $this->config->item('emailpassword'),
'smtp_port' => 25,
'smtp_crypto' => 'tls',
'mailtype' => 'html'
);
$this->email->initialize($config);
$this->email->set_newline("\r\n");
if($flag == 1) {
$this->email->from('someone#example.com', 'Someone');
$this->email->to('someone#example.com, 'Someone');
$this->email->subject('This is a test message');
$message = $this->load->view('email/firstmail.php', $data, true);
} else {
$this->email->from('someone#example.com', 'someone');
$this->email->to('someone#example.com', 'someone');
$this->email->subject('This is a test message');
$message = $this->load->view('email/secondmail.php', $data, true);
}
$this->email->message($message);
return $this->email->send();
}
So first email goes successfully but the second email fails everytime. Second email is not going delivered and giving false each time but first email delivered successfully. What is the issue here ? How can i get second email delivered successfully too in Codeigniter ?