Hey there

NIOS provides dual admission to those students who have passed their 10th and 12th class from a recognised board but their intention is to give that respective exam again for improvement in some subjects result. The candidate can give at least one subject on maximum 4 subjects exams. After passing the exam student can get only a single marksheet.

For more: https://www.google.com/url?sa=t&source=web&rct=j&url=https://school.careers360.com/exams/nios-class-12/amp&ved=2ahUKEwiHvc_O5NvzAhX6jdgFHWI1CPYQFnoECAkQAQ&usg=AOvVaw1qu8_XiZYephZEmr_-8jnq&ampcf=1