What if a icse board migration certificate is already issued but I got admission to another school of same board than do I need to cancel the migration certificate?
No, you don't need to cancel the migration certificate if you got admission to another ICSE school since both sThe migration certificate simply serves as a record of your academic history at the previous school. Your new school might request a copy of the certificate for their records, but canceling it would be unnecessary.
Schools are under the same board. Migration certificates are typically required when moving between different boards, not within the same board.
If you like to be certain, you can always check with your new school's admission office. They can confirm their requirements for transferring students within the ICSE board.
https://school.careers360.com/articles/icse-full-form
I hope it helps!