Actually, this just worked....
```
mysql> alter table quark_mac_addresses add constraint mac_address_range_id unique (mac_address_range_id, address);                                                                                                                                                                                                                                                         
Query OK, 0 rows affected (0.01 sec)
Records: 0  Duplicates: 0  Warnings: 0
```
I guess it's MySQL that's assuming mac_address_range_id when you run:
`'ALTER TABLE quark_mac_addresses ADD UNIQUE (mac_address_range_id, address)`