Hello,

If you're enquiring about JNU, New Delhi then at ug level it only offers BA Hons in Foreign Language such as Persian, Pasto, Arabic, Japanese, Koroean, Chinese, French, German, Russia, Spanish through CUET,

other than this it offers five years integrated dual degree BTech in CSE, ECE, ME, CE, Civil and Environmental Engineering through JEE Mains,

In case your query is for JNU, Jaipur the admission to BTech courses is done though entrance test conducted by the university followd by personal interview, admission or BSc Hons in Maths/Chemistry is based on the  merit of the qualifying examination, followed by personal interview, check out the official website at https://www.jnujaipur.ac.in/ (https://www.jnujaipur.ac.in/school-of-life-basic-sciences/programmes) to know more details regarding this,

UGC has recently allowed candidates to pursue two degree courses simultaneously in regular medium through same or different universities, however you need to take care of class timing and distance regarding this as well since attendance is an important criteria in regular mode study, else you can also go for one degree through regular mode and another through distance mode, this entirely depends upon you, so think clearly about the choices  you want to make,