Im willing to bet money they are. I agree with SN2. Think about it this way, how do you think they scale their tests? They may incorporate a passage or two from a test 2-3 years ago into a current test because the chances of someone seeing it twice is slim to none. Also if they do that they have an idea of how difficult the passage is already do the data from that test, and can use it accurately scale the newer test.
Do they reuse passages and maybe questions? Im willing to bet 100 dollars on it. Im sure some passages get frequently thrown out though like SN2 said and in reality they're asking some of the same questions 1,000 diff ways.