First answer:
create two seperate forms
<form action="page1.php">
<input type=button name=button1>
</form>
<form action="page2.php">
<input type=button name=button2>
</form>
Answer after OP commented:
use a "hidden" field in HTML which will contain the button which is pressed (keep it simple and use a single number like 1 is button 1 and 2 is the other button)
You put a javscript function on both buttons that will change the value of this field when being pressed.
In your PHP Script page where you land if you press the button you just do
if ($_POST[hiddenfield]>1)
{//button1 is pressed
}else
{//button2 is pressed
}
if you need help with the hidden field or javascript, comment and I'll show you the code