removing all duplicate values from an array

Hi, I'm looking for a function that does almost the same as array_unique() But it must also delete the other duplicate entry. sample to explain: array( 'a' => 'one', 'b' => 'one', 'c' => 'zero', 'd' => 'two' ); I now want the result to be: array( 'c' => 'zero', 'd' => 'two' ); This way I will be able to do an array_diff and then see all the duplicate entries listed. this is to find dup. ip address for a hosting system, displaying both accounts will make it easy to trace the amount of accounts 1 ip curruntly has. Anybody know how to do this? Thanks, Allowee