while I haven't read your latter textbook ,but basically there is not easy to learn both of them for beginner. as leo said, simplified is a trend.Even the language I am woring on, Japanese, they got some simplified chinese characters, like 国,学 instead of 國,學 used in HK and taiwan.( However most of them there are still traditional in Japanese )It seems I have been carried away! Anyway, I reckon if your textbook is for school, then just follows. If you are studying by yourself, then just study the simplified as the foundamental, and improve your knowledge for traditional ones later. You can learn them both for sure but always make simplified the first, I think it helps you get better with the study.