Removeing duplicates inside for/foreach loop.

$array = array( 1 => array("order_number" => "10DA0DDEDAF97DB", "order_payment_first_name" => "Mike", "order_payment_last_name" => "Smith"), 2 => array("order_number" => "10DA0DDEDAF97DB", "order_payment_first_name" => "Mike", "order_payment_last_name" => "Smith"), 3 => array("order_number" => "45Y3453245T23T5", "order_payment_first_name" => "Steve", "order_payment_last_name" => "Jobs"), 4 => array("order_number" => "34RTB345T45T456", "order_payment_first_name" => "Frank", "order_payment_last_name" => "Capra"), 5 => array("order_number" => "567U457645645Y6", "order_payment_first_name" => "John", "order_payment_last_name" => "Doe"), 6 => array("order_number" => "7698234T456M963", "order_payment_first_name" => "Bill", "order_payment_last_name" => "Williams")); echo('<pre>'); print_r($array); echo('</pre>'); My question is I want to remove duplicate order numbers in other words ditch *one* of the Mike Smith rows there's a duplicate order number there. And I need to do it in either a for/foreach loop. Somehow there's got to be a simple way to check and only output non duplicate order numbers while I'm looping thru the data. Any help would be greatly appreciated. Thanks php.code@tx.rr.com