Here are two form with two submit button:
<form method="post" action="page.php">
<input type="submit" name="btnPostMe1" value="Confirm"/>
</form>
<form method="post" action="page.php">
<input type="submit" name="btnPostMe2" value="Confirm"/>
</form>
And here is your PHP code:
if (isset($_POST['btnPostMe1'])) { //your code 1 }
if (isset($_POST['btnPostMe2'])) { //your code 2 }