sda has some data on it and I copied all data from sda to sdb using
dd if=/dev/sda of=/dev/sdb
Now, when I run fdisk on sdb, it reports as a 1024MB disk but does not let me add any new partitions; says that no free sectors available, even though another 512 should be available. Since its MBR has the partition table info of sda, a 512MB disk, I am getting this error. How can I fix the partition table (using some tool, not manually which I can do by myself) information of sdb without deleting any data contained in sdb (which was copied from sda)?