[CentOS] CentOS 7 disk identifier

Are disk identifiers important in CentOS? I have two disks that used to be in a Intel fake RAID1 configuration and I now see have identical disk identifiers of 00000000-0000-0000-0000000000. I now want to use only one of them and later use mdraid for a software RAID1 configuration.

Googling suggests that: (1) disk identifiers are /not/ important and (2) they are using the format 0x12345678. However fdisk -l displays the disk identifiers of my disks in the long UUID format. Further, another disk in the system does use a long UUID.

Last, googling suggests there is confusion between disk identifiers and partition UUIDs. I am specifically asking about the former.