You probably have already figured it out but it's the same logic. It's a more endearing/casual way of calling someone. Like, say if there's a full chinese name of 黄振豪 - the 黄 is the surname (last name?) and 振豪 is the given name. So a not so casual way of saying the name of a chinese is just saying the name as is.
If the person is younger than you and dear, can be called like 小豪, but if it's just a really casual way of calling the person, can be 阿豪.