Daily Identity stolen(?)

I've been asked a few times over the past months to reenter my leaderboard name. OK, weird but no problem.
However twice now I've opened the game and saw "Daily already completed" and my score on the leaderboard is definitely not mine.
So how would this happen? Does someone have my DD.net password, or was it possible through typing the same name on the leaderboard?
However twice now I've opened the game and saw "Daily already completed" and my score on the leaderboard is definitely not mine.
So how would this happen? Does someone have my DD.net password, or was it possible through typing the same name on the leaderboard?