I second this – I want to use the WP-About Author Plugin as it has more functionality. Because it references my profile info I need to have the info there, but when the info is there the built in about pops up so now there are 2, which is frustrating.
I really think that if the plugin you’re using is creating another author info box, it should be the one to hide the default WordPress one as well. This is not theme related, this is normal WordPress behaviour.
Anyway, an easy way to hide it via CSS would be this: