Assistance with setting up two IPs on one interface

For the longest time we have run QTSS and apache together on port 80, on two different IPs on one interface (en0) on one server. I notice the setup for configuring two IPs has changed on Snow Leopard Server, now it's done using the Network Control Panel on the left column. It used to be under Network>Location>New Location

We used to use for the primary IP/Apache the Netmask 255.255.224.0.

Then for the second IP, for QTSS, the Netmask 255.255.255.255. I had picked up this tip years ago on a server setup forum.

Is this still the recommended practice? Just wondering if it's time to use the same subnet in the secondary as the primary, 255.255.224.0, when on the same ethernet port.
Or does it not make a difference?
Thanking anyone for feedback.