Hi ConquertheGMAT,
The scoring algorithm on the Official GMAT is far more complicated than most people realize. As such, you shouldn't be spending time trying to figure it all out. Since that algorithm is proprietary, no GMAT company has an exact match for it, thus CAT scores can vary a bit based on the 'biases' involved in their respective designs. If you find that you're questioning the results from a particular 'brand' of CAT, then you have the option to use a different 'brand' - and there are plenty of reputable options to choose from.
A far more useful gauge would be to review each CAT and determine how many questions you SHOULD have gotten correct, but didn't (due to a silly/little mistake). Those mistakes are the things that you have to fix to score at a higher level.
GMAT assassins aren't born, they're made,
Rich