Hi
1) Multiple account on same device. Simple. Don't hit "remember my password" when you login, that way it will always ask you for your info. If you already hit remember my password, delete your game and install it again, then don't hit remember the password
2) No account has ever been lost or deleted. EVER. (knock on wood).
Ok, I replied this question multiple times so I thought it was solved but it just keeps coming and coming
It is always the person forgetting their email address or their password or entered a fake email or simply their device entering into autocorrect mode and adding some additional character to their info without them noticing.
I'm sure I'll have to say it again but if someone tells you that their account was deleted or lost, tell them that it's literally IMPOSSIBLE. (i get emails every day with this and I always solve it, it's as simple as that, tell them to write me an email).
One solution from my part is that when people register, not to allow them to play and just send them their password to the provided email. That way if it's not correct or fake, they won't play. I don't want to do this since there will be a delay, they'll have to get out of the game and check their email. But it seems to be the only way to avoid the "my account was deleted!" messages.