To add a second ip-number to an network interface create a new ifcfg file ex /etc/sysconfig/network-scripts/ifcfg-enp1s0f0:0
TYPE="Ethernet" BOOTPROTO="static" DEVICE="enp1s0f0:1" ONBOOT="no" ZONE=public IPADDR=80.67.x.x PREFIX=31 GATEWAY=80.67.x.x
The default configuration for that interface might have parameters such as UUID, NAME those are not needed. change ONBOOT to yes after testing the configuration. To test run.
systemctl restart network.service