If a browser sends more than one cookie to the server,
 only the first cookie sent gets parsed into a variable.

Reproduce with the following code:

---------
<? if ($set == 1) {
  SetCookie("first","apple");
  SetCookie("second","orange");
}

echo "[first:$first][second:$second]($HTTP_COOKIE)";
?>
<hr>
<? phpinfo(); ?>
-----------

when call it the first time with a query string of 
"set=1", I get two cookies sent to me, as expected.

When I try the page again, I get

[first:][second:orange](second=orange; first=apple)

as output. The other cookie is in $HTTP_COOKIE and
the output of phpinfo tells me:

HTTP Request Headers / Cookie is:
second=orange; first=apple;

but the value "apple" doesn't get parsed
into the variable "first".