Hello!

No it won't affect your marksheet. If you still want to take up nios exam proceed with that. If you don't want to take up nios exam then you can submit a candidature cancellation. If you are pursuing with nios exam you then you will have 2 marksheets. But NIOS are not recognised in every institutions. There are very few institution that will accept NIOS board marksheet. Whereas CBSE board marksheet is acceptable by all institution. CBSE is preferred over NIOS. ALL THE BEST. Hope the answer was helpful.

Thank You