1) first news about projected start date gets posted, whether it's from MEW or part of a related article, such as when a director or actor is attached, and they say in the article that "filming is slated to start in June of 2012". I usually count that as a projected start date and don't replicate it if it appears elsewhere (ie. MEW later lists the movie with a start date in the same time frame that the article gave). This, in my mind, usually means that the movie is one step closer to being a reality.
2) second news that states "production starts today" or "the film is now in production" is also posted, because that indicates that it's actually happening, and the stock needs to have its production status changed.
What you posted seemed to fall into the first category, and that type of news had already been posted and tagged. It was more of the "production will start soon" info, and not "production is now underway" stuff.
Keep in mind, this is my "rule of thumb" as I said above, and not the rules of the board, necessarily. Just how I have interpreted what I thought D.Mac's wishes are as far as duplicating news.