hey nikhil,

i would like to tell you that having a marksheet of  improvement with excellent grades is far better than having a marksheet with less marks ,as it directly indicates your potential of improving anything like yoiur marks

getting yourself enrolled in MBA program and having improvement marksheet of class 12th would be not a problem , as you can even get admission in MBA program on the basis of your graduation score however while appearing for entrance exams and some college also do demand 12th marks but they all do accept improvement marksheet so there is no worry to do.

good luck!