Help please account sign Up

Hey guys is it necessary for me the sign up this game using the same username as my Gamehag account? Im saying this because for other games like Crossout, War Thunder and game of thrones I got rejected for not registering a new account even though I did register and finish the tasks and the verification system said that all the games I played cannot have the same username as my gamehag account. But the problem is how does Gamehag verify the account associated with the completion of the tasks if you dont have the same gamehag username in other games.

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