It looks like you tried to attach disks from a higher release (probably 8.x) to a 7.x system without first removing them in an orderly fashion from the 8.x system. You might get things to work by doing this on the spares with bad labels:
Removing software-based disk ownership:
At the storage system prompt, list the disks and their RAID status. filer> aggr status -r
Note the names of the disks from which software-based disk ownership is to be removed.
Enter advanced privilege mode. filer> priv set advanced
Execute the following command on each disk: filer*> disk remove_ownership disk_name filer*> disk remove disk_name
Exit advanced privilege mode. filer*> priv set
Verify the disk(s) show as 'Not Owned'. filer> disk show -v
Any disk that is labeled 'Not Owned' is now ready to be moved to another storage system.
Normally, this should be done before you remove the disks from the first system. If you can get this done on your current system, then re-assigning ownership should get you where you want to be.
I'd suggest an upgrade to something a bit newer than 7.2.4L1 as well... like 18.104.22.168
I remember having a similar problem with some disks pulled out of 2040 (DOT 😎 trying to put them to use on 2020 (DOT 7.3). I tried Maintenance Mode (remove label), unfailing them with advanced privileges, releasing them, etc, but it didn't work because the labels were for DOT 8. In the end I placed them back in 2040 and performed revert_to process from 8.0 to 7.3 which renamed the labels to match that of 7.3.