its not worthy to mention that we see website with different language option but if we talk about content duplication than where do we assume our selves, as the content against the both (or more) languages is same?
Technically yes it would be classified as being the same piece of content, but through translation many things are mis-interpreted so in essence it could be similar but not exactly the same.
Translating content into different languages is not content duplication. Its more of a content plagiarism than content duplication. And Search engines are not programmed to calculate plagiarism right now. Although, the content generated by auto-translator (if you are using one) is sometimes not as good as it needs to be due to bad readability, poor sentence formation and grammatical mistakes. It will be good for you to proof read the content and rectify the errors (automated translated content follows the same rules that are followed for automated content generator)
thanks for your view @rebecca but i'm actually worried about it because of "google translator" as it converts in so many languages so how should i assume that the google is not that much efficient to read the similar content of different languages?
Don't worry, they're not nearly that advanced. What I'd worry about is having your site indexed in X different languages when you really only value SERPs in one country. You can always noindex the translated pages.