Finding unique keys in array

[lobobr]

I have an array that goes like this:

$myarray = Array(
                              "Name" => "Fred",
                              "Age" => 30,
                              "Name" => "John"
                              "Age" => 25
                            );

How can I get only unique keys in this array.

I've tried:

foreach(unique(array_keys($myarray)) as $k)
{
    echo "$k<BR>";
}

and it outputs nothing...

And tried:

$mykeys = Array(array_keys($myarray));
$unique = array_unique($mykeys);

doesn't work, still prints two times the keys...

Please HELP!

[paulnaj]

What about ...

$myarray = Array( 
    "Name" => "Fred", 
    "Age" => 30, 
    "Name" => "John", 
    "Age" => 25 
);
$unique_keys = array_unique(array_keys($myarray));
echo join("<br>", $unique_keys); 

(Just to say ... your example array has got a comma missing after "John").