In another shot you can actually see there are two ships on the left side that appear to be YT-1300s.
So, it is positive that one of them is just another YT-1300.
As for the other one, probably not. There are a lot of sites that say the YT-1300 seen in Revenge of the Sith has been confirmed by Lucas to be what will eventually be called the Millennium Falcon. But he never made such a confirmation on either of these two YT-1300s from Attack of the Clones.
In fact, the often quoted (and yet never cited) claim from Lucas goes something like this:
George Lucas confirmed that it was the Millennium Falcon itself and not just another ship of the same class. - http://starwars.wikia.com/wiki/Millennium_Falcon#Behind_the_scenes
YT-1300s were probably more common before the rein of the Empire.