Normally I wouldn't really see a problem with this, because as far as I understand the numbers are just there to show a tier on how powerful the graphics cards are, and since this is the 6990M, one would assume that it's the highest tier for the current generation mobile graphics card.
Now on the otherhand they're using the numbers as their desktop counterparts just with a tacked on M for mobile, I assume the only reason they don't use a different number is because it could confuse the buyers into thinking it was either a newer or older generation part, although that's assuming most people who buy these know what the current generation parts are(which I assume is not the case).
What you're seeing isn't actually them trying to deceive people it's actually them using a streamlined approach. All this 6990M means is that it's top tier for mobile GPU's of the current generation, this is the consequence of trying to make the numbers more buyer friendly. Good Idea, Good Usage, but relies heavily on customer knowledge and understanding on what they're buying, but that could be said for almost anything.