does it mean that there are two boxes? one for the set-top box and the DVR box itself?
The series 2 has a cable ready analog tuner built in to it. If you only want to record non-scrambled analog cable programing, then you can connect your Tivo directly to the cable jack. If you want to record premium (scrambled) analog programs or digital programing, then you need to use a cable box. The series 2 included an IR Blaster which can be used to control a cable box.