How to change filesystem UUID (2 same UUID)?

I have a fedora guest OS in VMware. I want to expand /boot partition, so I add another virtual disk to this VM, and try to clone the disk. After dd if=/dev/sda1 of=/dev/sdb1, blkid report that /dev/sda1 and /dev/sdb1 have same UUID/GUID. It's weird that there're 2 same UUIDs in the universe, how to change one of them to another UUID value? Update 2017-01-25 Subject changed, UUID here means filesys