htaccess rewrite rule loads assets twice?

Question

I am using these rules:

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_URI} !\..+$
RewriteCond %{REQUEST_URI} !(.*)/$
RewriteRule ^(.*+)$ /$1/ [L,R]
RewriteRule !\.(js|ico|gif|jpg|png|css|html|swf|flv|xml)$ index.php

But when I check resources loaded in chrome, I can see that my .css files are loaded twice.