When you are into writing your blog and to develop as an important entity in your business. It is better to follow the guidelines and rule of the game of Google. And that too when Matt Cutts by himself stated not to create a Duplicate Meta information it is a critical input by Google in saving your website from penalty of Google.
Rather Matt has stated to either not to have a meta description at all as compared to having a duplicate meta description. Hence worth as per Matt meta tag description of your blog should either be unique or not to have a meta tag description at all. In fact Matt has took example of his blog wherein he never places meta tag description at all. Matt also mentioned that Google snippet will by itself generate a better and unique meta description and will also it is not much a effort to actually worry about meta description. Only if it is your home page or a page of big importance for you like product description page. Which is actually influence people to opt for your product and service. The meta description is an important factor which determines the relevance of your page and as we discussed in keyword in description tag it is an equally important factor. But when your blog is becoming more and more loaded with contents it becomes important you keep every post equally different not only in terms of the content and the context it should be equally different from meta description as well. Henceforth when you are writing a very important page equal efforts required in keywords, meta description and relevance. Duplicate meta information not only drops a single page ranking but also it will carry the ranking of all the page down due to duplicate meta information.