Thank you for this bug report. To properly diagnose the problem, we
need a short but complete example script to be able to reproduce
this bug ourselves. 

A proper reproducing script starts with <?php and ends with ?>,
is max. 10-20 lines long and does not require any external 
resources such as databases, etc. If the script requires a 
database to demonstrate the issue, please make sure it creates 
all necessary tables, stored procedures etc.

Please avoid embedding huge scripts into the report.

works for me..

<?php

$unique_terms = array('a', 'c', 'd', 'b', 'c', 'b', 'c', 'd', 'b', 'c', 'd');

print_r($unique_terms);
$unique_terms= array_unique($unique_terms);
print_r($unique_terms);exit;

Array
(
    [0] => a
    [1] => c
    [2] => d
    [3] => b
    [4] => c
    [5] => b
    [6] => c
    [7] => d
    [8] => b
    [9] => c
    [10] => d
)
Array
(
    [0] => a
    [1] => c
    [2] => d
    [3] => b
)

are you using any kind of zend_extension ? are you sure the "conflicting 'c'" does not have spaces or other chars inside ?

Thanks!
I've dumped the variables (var_dump();) and it seems that there was a trailing newline (because of fscanf) from the windows vs *nix formatting. It seems that print_r didn't append this newline character into the formatting.