Project name:Test Board(B)
Board Name: TB Board
Copy name: Copy TB Board
If i am delete the issues in Copy TB Board,the same issue is getting deleted in TB Board
Again, boards are not containers.
If you copy a board, it's going to show the same issues as the source board, because it's selecting the same issues from the list. It's nonsense to expect a copy to "not have any issues" because you're copying something that is configured to show the same things.
Please, think again about what a board is.