When you accept membership in someone else's blog, you are going to use a different browser, than the one used by the owner. If you are accepting membership in your own blog, as part of a blog ownership transfer that you started, you might be tempted to use one browser, for the entire process. If you do this, you can end up with a blog owned under your current Blogger account - but using your (would be) new account's email address. This may cause you to lose control of the blog. If you manage to retain control of your blog, you'll continue to use the current Blogger account - as the new Blogger account will never get control.
What Blogger won't tell you