I have two separate blogs, registered to the same username. I want to appear as author name 1 in one, but as author name 2 in the other.
Yes but read on so you understand. When we register a username we supply an email address that becomes our unique identifier. When we are logged in under that username account and register a blog it will be registered to that username. We can create a "nickname" or "display" name but it will appear on all blogs registered to the same username account.
In order to completely separate the blogs that are not associated with each other you register another username account using a different email address when you are logged out of WordPress.com. Then you add the new username account as an official user of the blog, and designate them as an Admin. Next you transfer one of the blogs to the new username account using this process.