Is this normal when using a Kaplan book?

When I took the pretest in the beginning of each book, I got a 780 for US history and a 770 for Lit. I heard that Kaplan makes the pretests harder than the actual test in order to ensure a higher score. I just finished taking the final practice tests, after reading through the books entirely and studying over the past two months, and I got worse scores. My predicted score is now 700 for US His and 710 for Lit. Is the Kaplan pretest a better predictor for the actual SAT Subject Test or are the practice exams in the back of the book? I’m kind of worried about my actual test scores now, and my test is tomorrow after being postponed from January…