That was on my laptop. On my desktop, I have FF 32.0.2, and I don't have the double login problem. I haven't added the FF add-on either.
I looked at the link I got after I clicked 'Log in or Sign up' and it looks like this: https://auth.soe.com/login?service=https://forums.station.sony.com/eq/index.php?login/login I removed the last bit: https://auth.soe.com/login?service=https://forums.station.sony.com/eq/index.php?login and got in with just typing my log in and password once. delete the %2Flogin from the end of the url. It has login twice, it should only be once.
Same here....a lot of sign in websites also allow you to remain signed in for a certain amount of time so if you close the browser on accident or go to another site and back your still logged in. That would be nice here.