I'm not familiar enough with O2's routers or your specific setup/kit/details to have a clear answer for that, although O2's network is based off BE Broadband's platform and they sell packages that can cope with multiple IP's (static and dynamic) so it follows that some of O2's services would have similar flexibility.
You can have more than one IP per physical internet connection, just as you can assign different IP's to multiple different computers from your router. The details of how this works depends on your software and hardware so that's not something we can dig into.
Mark 'Winter' Jackson
Editor-in-Chief - ISPreview.co.uk