Please be aware that beginning on April 2, 2013, logging in to the game or website will require your Display Name. Email addresses will no longer be accepted; your Display Name will be the only accepted option.
You are actually decreasing security using display name, not increasing it.
To be secure compliant logon name has to be unique and not shown to whole world.
It may create some fuss in the begging , but please add different logon name.