Tweetz showing repeated RT's


Appears that something may have changed in the past few days with the Twitter API. I am seeing RT's of tweets that I have already seen since I am following the original sender. I am not sure if it applies to Twitter Retweets and generic RT's, but I just received one that shows as being sent by Twitter for iPhone.

Example: http://twitter.com/Rob_Pardo/status/251821559327621122
This was then retweeted by http://twitter.com/FubarNick
I am following both people, and I saw the tweet in my timeline on Tweetz twice.

Hope this is enough information.