The new retweet API should take care of this problem. My understanding is that it will collapse all retweets of a message into a single message. So, if you are

The new retweet API should take care of this problem. My understanding is that it will collapse all retweets of a message into a single message. So, if you are following the original person who was retweeted, you won't see the retweet at all. Otherwise the original tweet is going to be added to your timeline once.