<?php

function one () {
}

print "Before\n";
function one () {
}

print "After\n";

?>

Using PHP4b2 running this script produces

Content-Type: text/html
--------------------------
Content-Type: text/html

Before
--------------------------
no errors or dump.

Running the same script with php 3.0.11 produces (as expected):
---------------------------
Content-type: text/html

Before
<br>
<b>Fatal error</b>:  Can't redeclare already declared function in <b>bug.php</b>
 on line <b>8</b><br>
-----------------------------