PHP根据键从多维数组中删除重复项

{ ["upload/example.gif"]=> array(5) { 
     ["title"]=> string(12) "This is me" 
     ["excerpt"]=> string(24) "This is a photo of a tree" 
     ["img"]=> string(42) "upload/example.gif"
     ["link"]=> string(23) "http://www.google.co.uk" 
     ["source"]=> string(6) "custom" 
   }
}

$array

$array = array( ["upload/example.gif"] => etc....
                ["upload/tree.gif"] => etc....
                ["upload/example.gif"] => etc....)

["upload/example.gif"] => etc....

$array = array_map('unserialize', array_unique(array_map('serialize', $array)));