Negative initiate a backup while system is taking another backup

1. Start a VM backup, bk-1 of a VM which has data d1
2. While the backup is in progress, write some more data d2 in the VM disk and initiate another backup bk-2.
3. Verify the backup 1 and backup 2

Expected Results

1. Backup bk-1 should have only d1 data
2. backup bk-2 should have data d1 and d2