Perhaps that's what it's supposed to do, but if username is turned on, it doesn't select any Name values at all, whether it finds a username or not. For example, if I type in an exact name, it doesn't find that in username but it also doesn't select the name from the Name list nor send an invite.
Even still, there's no reason it shouldn't continue on and find both. Supposing I was trying to find someone named Mark but the system first found a username marksomething then I wouldn't be able to invite the other Mark. I don't think that's the way it should work. Anyway I've just turned of username for now.
Also, a nice to have would be the ability to select users to invite from a (search) CB List. Our application uses lists to identify people with certain specific skills in specific locations so that we can invite them to participate in a community group, So I'm not inviting by name necessarily, rather by other search criteria. Like I said, this would be a nice to have. If you ever feel like doing some voluntary work for a not-for-profit, feel free to look us up Partners for Prosperity.