There is no bug here, this is user error. Your prior account was created with different credentials than what you are currently using. What happened is that you signed in with what you thought were your credentials for your account, but you entered a different account that bungie.net hadn't seen before. It then took you through the account creation procedure, and you created a new account. Recon's advice is correct - you need to log out of your account, and log into whatever credentials you used when creating your original account. Unfortunately, if you don't remember what those are, we can't help you. Bungie.net doesn't actually store your login or password, we rely on external providers like Microsoft, Sony, Facebook, and Google to validate your credentials.