It's been my experience that if you're going to have additional languages on your site, you can do one of a few things to the URL:
or
or
Then you can place the content in the respective languages on those sites. They won't necessarily be seen as duplicated content (semantics change as you translate to different languages). However, Google won't necessarily penalize you if you keep your URL to site.com and just switch up the languages because, again, semantics change as you translate languages.
I worked with several sites that translated content from English to Spanish or English to Hebrew and they were never once penalized for duplicated content.