Question for gurus - scoring the two sections partly

Hi guys,

I'm practicing with Princeton Review, which it seems to have several supporters here on gmatclub, and I have the following doubt:

Doing the full text, first quant part and the verbal part, I get: 590 (Q:42; V:30). After that, I write down my questions.

Then I repeat just the quant part (taking care of reviewing that I get the same questions, which is true), answering the same as I did before. I get 380 (Q:42; V:0)

After that, I do the same with the verbal part (again, I check that I get the same questions, which is true) and I get 300 (Q:0; V:30)

One question comes to my mind: is not the sum of the quant and verbal parts the overall score?

590 <> 380+300

Any suggestions to this?

Cheers