Having two regular degrees of intermediate from different boards

Many students do it for the purpose of improvement and there is no illegality in this. There are no regulations in our country which prohibit a student to do so. The problem comes only when you try to do it in the same year from 2 different boards. That is not permissible.

Moreover by appearing in class 12 exam again after 1 year you have in fact lost one year of your valuable student life. By that time the other students have might completed 1st year of graduation. What improvement you got is after sacrificing 1 year.

It is almost 8 years since you have completed your 12th. Students after 12th CBSE, at times, decide to try once more to get a better score. After CBSE, improvement exams or state board can be taken after one year. Simultaneous regular CBSE and state board is not allowed.
You have not submitted the CBSE anywhere for your higher education. So, as long as you satisfy the age criteria and proof of year's gap between the CBSE and the board exams of 12th, you should be fine.

There is no problem. You are using state board intermediate qualification only. Go on using that only for all purposes. Don't use one here and one there like that. Go with one certificate only. There is no illegality in what you have done. No worry. Go ahead with positive mind.Everything will be good for you.

From the initiative, which you have taken by reappearing in the UP Board for the improvement purpose, it is alright. Moreover, your CBSE of class twelve has not been utilised further no where. In such a situation no complications would arise from any corner.
However, during the such process, you have wasted a precious year in getting the degree of the graduation.
However, go ahead for your per suits with a positive mind.

There is nothing illegal in what you have done. In fact, you don't need to hide your previous degree. Secondly, by using the degree from the second attempt is used in college admissions, you are not at all in fault. It is because as per the rules, you should use the results or marks you obtained in the last attempt and it is applicable for all such kind of examination and even for many national level competitive exams.