Hi Jiřà Veselý.
Thank you for your response.
I am aware that there are several options available to provide control over itemids in v1.4., but neither of them solves the duplicate url problem.
The option "Exclude source info" may be used to exclude the Itemid variable from the URL and thus eliminate the duplicates caused by it. However, ignoring it completely may lead to unwanted Joomla! functionality, like not swithing the templates as desired or so. Whether this will be a problem for you or not depends mainly on the way how your site is designed and how complicated it is. If you need to fix this, the Itemid should be "reappended" to the SEF URL as an extra part using the option "Reappend source". Then the resulting URL will look like
yoursite.you/article.html&Itemid=xy.
But, "Reappend source" does not solve anything. After you turn it on you get the following urls for the SAME content item:
yoursite.you/article.html&Itemid=xy
yoursite.you/article.html&Itemid=xz
so, it generates duplicate content again.
I know that some people must think that I put too much importance on this duplicate content thing, but since JoomSEF is search engine friendly component, I think that this issue must be addressed. I cannot think of anything more SE unfriendly duplicate content all over your site.
Kind regards,
Zeljko