Fake is kind of a weird way to describe valid combinations of usernames and passwords that can log into Twitter.com. I would assume that if your account hasn't been disabled for whatever reason, it's a real Twitter account.

Twitter, however, does call these accounts "fake" and has further rules/policies concerning Misleading & Deceptive Identities.

https://help.twitter.com/en/rules-and-policies/twitter-imper...