How is your robots.txt file configured?
I found one file here
[url]http://svn.oxid-esales.com/trunk/robots.txt[/url]
this is for other cart, what interest me is
in bottom
Disallow: /?cur=
Disallow: /&cur
As I understand this would remove domain.com/product.html¤cy being indexed and understood as duplicate link?
What do you think of disabling
index.php?dispatch=checkout.cart
and
index.php?dispatch=checkout.checkout
?