Two identical URL's but different order in parameters: Duplicated content?

My own CMS automatically adds new parameters to links in a page to specify a given language.

It works quite well but it doesn't always put the var in the same position, giving me a link to same page/language:

www.xxx.yy/index.ph开发者_如何学Pythonp?mod=blog&page=3&lang=en

or

www.xxx.yy/index.php?mod=blog&lang=en&page=3

Will search engines be smart enough to detect both urls as the same? Or will detect as two different urls and therefore mark them as duplicated content?

I will fix this issue anyway, but I'm curious about this since long time ago.

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Google definitely supports this, as they explicitly mention that example in their webmaster blog:

Like www.example.com/skates.asp?color=black&brand=riedell and www.example.com/skates.asp?brand=riedell&color=black. Having this type of duplicate content on your site can potentially affect your site's performance, but it doesn't cause penalties. From our article on duplicate content:

Duplicate content on a site is not grounds for action on that site unless it appears that the intent of the duplicate content is to be deceptive and manipulate search engine results. If your site suffers from duplicate content issues, and you don't follow the advice listed above, we do a good job of choosing a version of the content to show in our search results.

For all other duplicate content worries, consider specifying a canonical url.