Hi , kcet and neet are two different things . NEET is for students who wants to get a seat in MBBS,BDS,BHMS, VETERINARY etc . It is done on all india level for students whereas Karnataka Common Entrance Test (KCET) is conducted for admission to the full-time Engineering, Technology, BPharma, DPharma, Agriculture courses (Farm Science) and Veterinary courses, in the various educational institutions in the state of Karnataka. So NEET is an all india level exam and kcet is state level exam . So if you'll appear in NEET you have chances of getting admission in college outside Karnataka as well whereas if you appear in kcet you have to get admission within Karnataka . These are two different exams and not appearing in kcet won't effect your result or counselling procedure of NEET .
Hope this helps