I'd imagine so. If you're talking about WordPress.com, then I'm fairly certain it's a one-blog-one-account kind of service. You log in with the name of your blog (e.g. if you register foo.wordpress.com, your username is foo).

It's possible they introduced some sort of multiple-blogs-per-account system, but of course you could just make two separate accounts. I doubt there's a limit on Blogger imports or any way to trace them back (unless you leave the Blogger sites up and people Google what you've written). If Google decided to be nice for a change, it should just spit out an XML file of your articles that you can import into WordPress.