Yes I know this happens, after you login you are redirected to the page you were on previously.
Now when you type the password wrong and go back to login page and type it right, your previous page was the login page. so after you login, you get redirected there. But you're already logged in, so it just tells you "you're already logged in".
This is admittedly, poor coding on my part really. I wrote this code may be 5 years ago or something.
ps. i don't think I ever wrote "log in" so many times before