Try separating the sendTo()
function with commas in a string:
$mail = new Mail();
$mail->protocol = $this->config->get('config_mail_protocol');
$mail->parameter = $this->config->get('config_mail_parameter');
$mail->hostname = $this->config->get('config_smtp_host');
$mail->username = $this->config->get('config_smtp_username');
$mail->password = $this->config->get('config_smtp_password');
$mail->port = $this->config->get('config_smtp_port');
$mail->timeout = $this->config->get('config_smtp_timeout');
$mailText = html_entity_decode($mailText,ENT_QUOTES, 'UTF-8');
$mail->setFrom($this->request->post['email']);
$mail->setSender($this->request->post['name']);
$mail->setTo($admin_alcudia.','.$admin_palma);
$mail->setSubject(html_entity_decode('Se ha realizado una solicitud de reserva', ENT_QUOTES, 'UTF-8'));
$mail->setHtml($mailText);
$mail->send();
This should eliminate the need to have duplicate code.