This idea is somewhat present in the ending of the first book already, the second one just spells it out, but the second book has a character shitting on Alan Grant for his ridiculous idea that a predator wouldn't see you if you're not moving, speculating the T-Rex was probably fed at that moment (which is accurate). And the whole idea of there being a second island for growing the dinos is treated as obvious by the same character, since the small lab they were shown in the first one is obviously just theatre for the visitors. So yeah, Crichton was not above correcting his earlier mistakes.

I highly recommend both books. They're awesome, and they diverge from the movie in many ways - notably not all survivors from the movie make it and vice versa, so it's still very suspenseful even if you know the movies.