Hi honneeey,
I'm sorry to hear that Test Day did not go as well as hoped. From what you have described, there are some aspects of your studies that likely impacted your performance.
To start, the process of taking (and reviewing) a CAT requires a significant amount of energy and effort - and takes time to 'recover' from. This is one of the reasons why you typically shouldn't take more than 1 CAT per week - and your last CAT should be taken about 1 week before Test Day. By taking two CATs in the 2 days before your Official GMAT, there's a reasonable chance that you experienced some 'burn out' on Test Day.
In addition, GMAC has publicly stated that the Official Score that you earn on Test Day is within +/- 30 points of actual ability. Your 2 Official Scores are similar-enough to one another that you essentially performed the same each time (about 640 +/- a few points) - even though you took the Tests about 1 year apart. You handle certain aspects of the GMAT consistently well, but you also make certain consistent mistakes.
Thankfully, the GMAT is a consistent, predictable Exam, so you CAN train to score at a higher level. Before I can offer you the specific advice that you’re looking for though, it would help if you could provide a bit more information on how you've been studying and your goals:
Studies:
1) How long have you studied for this recent attempt?
2) What study materials have you used so far (including materials that you used for your prior attempts)?
Goals:
3) When are you planning to apply to Business School?
4) What Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich