If that's the case, I guess FJ should have indicated you on the first day of your registration that your account has been made over a same IP or something like - you cannot create more than one account here from same IP. Your account should have been either banned or you should not have been given the chance to create an account there (which would make it clear for you that your IP address belonged to someone some time ago and they accessed as well as may have already created an account there) and you could have tried with a different IP address if such warning would have been displayed.
That is not how it should happen or how FJ should act in such a situation, it just isn't. What you are saying is basically that FJ owes it to their potential customers to let them know they need to take more precautions to abuse their site by saying "Oh hey you've already used this IP, go find a different one and come back". You understand how silly that sounds, no?