NIOS 12th

Yes, the two marksheets of CBSE and NIOS are valid to take admissions in any Engineering college. NIOS result is equivalent to CBSE and NIOS is authorized by the HRD (Human Reseources Department ) of Government of India. But the most important mistake that is made by most of the NIOS apperaring students is if you want to join good college but marks in any of your subjects ( for example., Maths) is very less or result is not declared, you should appear all the exams ( Physics, Maths, Chemistry, English ) not only in the particular subject which you have scored less. So that you can be eligible for the admissions in most of the colleges. But there is also a few of private institutions which accepts the scores of independent papers based on the state and colleges you want to get admission. But the main condition is you must have to clear the language paper in NIOS. Concluding that, if you have cleared Maths along with other subjects through NIOS, you are 100% eligible for admissions in private colleges .But if you want to join Government colleges, you have to look into the particular state's  eligibility condition for college admission. For eg, in Tamilnadu, you couldn't take admission through NIOS.But, it is highly possible if you cleared all the exams through NIOS in other states.