I had to clear the browser cache to see what you can see.
Indeed, it looks like an extra t-shirt. When you type 646097-340 in Google Images you should be able to see its front.
Frankly, this is surprising. For the last 2 years, there was only one post-US Open outfit, and it usually came with the Winter/Holiday collection. Getting a separate outfit just for one tournament (i.e. Cincinnati) seems like an overkill. Perhaps it is for the Asian swing. On the other hand, you can see the color palette is the same as the current outfit's (white (top), black (horizontal line), green strike (front), soar (swoosh)).
Nike seems to be really milking Nadal this year (ironically, one which proves one of the worst of his lustrous career). They seem to have become lazy too. One design for the entire year, and, from what I have read somewhere on this forum, he will sport the same design in the next AO, too. Go figure...