Which Bluebook practice test is closest to the actual SAT (difficulty-wise)

So far I've taken two Bluebook sat practices in preparation of my March 9th SAT. Reading seemed about the same difficulty-wise for both, but for me math was way harder on the second practice test. This is illustrated in my test scores; I got a 700 in math the first time, and a 600 in math the second time. (Despite a week or two of studying in between)

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Has anyone had this same experience?