CSS nevaru uzlikt 2 background image

Šodien nolēmu taisīt savu web lapu sākšu ar CSS
un redz kur problēma:

<html>
<head>
<style type:"text/css">
body
{
background-image:
url('....');
background-repeat:
repeat-y;
background-position:
right;
background-attachment:
fixed;
url('....');
background-repeat:
repeat-y;
background-position:
left;
background-attachment:
fixed;
}

</style>
</head>
</html>

kā uzlikt viena bilde vienā malā otra otrā ?