we are implementing new feature on our site - private accommodation listings. We would love to have it in multiple languages, but possibility of google seeing this as a duplicate content worries me now.

Further info:
default url is like this:
www.domain.com/accommodation/specific_client/

accommodation presentations are made in php and are wrapped inside of a str_ireplace function. Clicking on a little flag (let's say French) in the header loads a new url:
www.domain.com/accommodation/fr/specific_client/
Function reads the "fr" part and loads French words instead of English ones. We are able to do so cause words are static, like: distance, price, area, region etc.

Anyway that's all good, but what troubles me is what does all mighty google think about this? Because all these url's like:
www.domain.com/accommodation/specific_client/
www.domain.com/accommodation/fr/specific_client/
www.domain.com/accommodation/sp/specific_client/
www.domain.com/accommodation/de/specific_client/ etc,

are the same. I mean style sheets are the same, margins are the same, pictures are the same... everything except the actual words.
So we are surely having duplicated code.

Should I proceed with these or would you suggest to avoid the risk?
I guess I could block all "specific language" pages in robots.txt and leave only the english one as the default spider food, but then again is it worthed if no one will ever find it except users who come to the site?

All in all, thanks for reading : )