Curious why you need multiple IPs, care to share? If you want to hide the IP address(s) just put CloudFlare in front of it and don't leak your source IP. It's a WAF, but works a lot like a reverse proxy. Maybe you can get away without multiple IPs.
So I am not a networking guy. Maybe naively, we have it set up so the box is running and reverse proxies various website-lets of our website. Then we have an ip for the idrac, which can control the box, check it's status. With vflash, we should even be able to load and install new OS's onto the box all remotely. (In fact this is something I / we want to experiment with...) So the idrac is really a separate ip to keep things not too confusing. (I gather for Dirac 7 you can have a pass through? so the same box can share the same ip between the main box and the idrac...? I am not sure about this...)
Then for setting up things like mail etc it is nice to be able to use some of the installers out of the box. Of course you can get around a lot of things with port mapping etc... and then the final reason is we have multiple boxes.
It would be nice to be able to ssh experimentalbox1.myhomeufb.co.nz and ssh experimentalbox2.myhomeufb.co.nz, and not have to put in a port mapping there... etc.