Hi Nilabh, it's actually neither legal nor illegal to clear exams from a single board in one year and the other in the next. However, since every boards have a different perspective and pattern of imparting education. It's advisable to stick to a board that make you comfortable with. Also, if you've failed in one subject and cleared all the rest, you could have a chance to re-appear in the compartment of that subject too.
If you wish to attempt the subject in other board due to some genuine reasons and further, you could always seek support from your school staff and principal accordingly.
Hope this helps.
Thanks. Wish you a lots of success ahead!!
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