The name of the painting didn't change, it was just misreported. People thought the two halves of the phrase were alternate titles, when in fact they were a single continuous title.
Indeed, perhaps the true title was deliberately misreported (by the Curator?) in order to conceal Gallifrey's survival from the universe at large. It's amazing how much you can mislead people just by nuancing how you report something.
I'd buy that theory. Works for me!