checking again the doublicate urls issue, I found out, that the extension &vmcchk=1 causes double urls.

Example:
index.php?option=com_virtuemart&Itemid=4&category_id=6〈=de&page=shop.browse

and

index.php?option=com_virtuemart&Itemid=4&category_id=6〈=de&page=shop.browse&vmcchk=1

same thing, but a ~2.html link.

What can we do?

Hello,

yes, this can be the cause of the duplicate URL. The only solution would be to add this variable to the list of \"non-sef URLs\" and run JoomSEF with \"Append non-sef URL\" setting set to \"yes\". Then the variable will not be stored in DB, but will be appended behind the SEF URL in case, it is present.

Best regards,
ARTIO Support Team

Hi,

mmmh: 1.The only solution would be to add this variable to the list of \"non-sef URLs\"
>Where can I do this????

2. run JoomSEF with \"Append non-sef URL\" setting set to \"yes\". Then the variable will not be stored in DB, but will be appended behind the SEF URL in case, it is present.
>First part is clear, but what does it mean for google? O.K. it isn't stored in DB, but does Google put both in their DB. The main problem isn't that I have double url's, it is that Google has double urls in their DB. That's the main problem. Can I avoid this anyhow?

Vmcchk is a variable added by VirtueMart and used for checking if cookies are enabled in users client agent.
You can disable this in VirtueMart Configuration / Core Setting / Enable the Cookie Check.
By disabling this, vmccchk will not be appended to URLs.