PHP - Uniqid

Hi guru's,

I was just playing around with formtokens by using the function uniqid(); (is this btw unique enough for a form token?)
pretty soon i noticed something weird: I have this small script (for testing)

<?php
   $token = uniqid;
   echo $token;
   //resulting in something like: 4cbba625bd06d 
?>

Now for some reason if i run this code no matter how often the first few characters are always 4cbba
Anyone has an idea on why/ how et cetera?

So 2 questions:
- is this function good enough for creating a secure form token?
- how/ why does it keep starting with 4cbba?

Would love to here it, thank you 

I have a form on page 1 that submits to page 2, then on to page 3, 4 and 5. On each page more data is collected, then page 5 puts it all into its respective place in the database.

I'm trying to prevent a duplicate entry from someone hitting the back button, and I've seen suggestions to do it with sessions and a uniqid.

I'm not versed in sessions, so my first question is, because I'm not submitting to the same page, where do I put the session? on page 2 or page one?
Right now, on page one, all I have is:

Code: [Select]
<?php session_start(); 

include("dbconnection.php"); 
?>

<!-- a bunch of  javascript form validation, html code and the form -->

<?php
  
 $unique_id = uniqid (rand (),true);
  $_SESSION['unique_id']=$unique_id;
  ?>

<form name="register1" class="registration_form" method="post" action="register2test.php" target="_self" onsubmit="return myForm()">
<input type="hidden" name="unique_id"  id="unique_id_form" value="<?php echo $unique_id; ?>"  >
<input type="submit" value="Submit"  class="buttontype"/>
</form>


on page two, I'm assuming, it's something similar to...

Code: [Select]
<?php
session_start();

if (isset($_POST["submit"]))
{
    if ($_POST["unique_id_form"] == $_SESSION["unique_id"])
    {
        $_SESSION["unique_id"] = '';
       /*set variables here ? */    }
    else
        echo 'error';
}
else
{
    $_SESSION["unique_id"] = uniqid (rand (),true);
?>