Hey Meenaloshini!

You can do either of them:

1-Ask your school authorities, or the coaching authorities, who gave you the original hall ticket . They'll provide you the copy. Or else, they'll handle the situation.

2-If not possible, write a mail to CBSE(or to the board with which you are opting your 12th from) regarding the same.

First one will definitely work. Don't stress out too much.

Best of luck!

Hello aspirant,
Yes, you can use a duplicate copy.
However, most of the schools never give the original hall ticket to students in the begining.
They give after or in the end of exams.
You may contact your school for helping you.
You may also go on tge official website of the board you are pursuing.
CBSE/ISC/State board.
All the best.