link two php pages on form submit with action tag

You cannot do it the way you want, but what you can do is :
simply create a function that does the task of npcc_sendmail.php and then re-write some part this ways:

<form name="form1" method="post" action="npcc_details.php">
</form>

in npcc_details.php include the file npcc_sendmail.php function. and then call the function with required parameter.

I wanted to show another way, but it didn't work as I expected. It creates a new window, anyway, try the above one :)

Well, the second one is added. Simple example, you would understand

<script>
	function submit_()
	{
		document.forms['you'].action="x1.php";
		document.forms['you'].target='x1_';
		document.forms['you'].submit();
		document.forms['you'].action="x2.php";
		document.forms['you'].target='x2_';
		document.forms['you'].submit();
		return false;
	}
</script>
<form name='you' action='' target=''  onsubmit='return false'>
	<INPUT TYPE='text' name='test'>
	<INPUT TYPE='SUBMIT' name='SUBMIT' onclick="return submit_()">
</form>
<iframe id='x1_' name='x1_'>
</iframe>
<iframe id='x2_' name='x2_'>
</iframe>