there was an issue in the recent patch that possibly allowed certain classes to fight their mirror multiple times, and each time they won, they recieved another 50k xp, so they are fixing it, should be up soon
It's true, there was an exploit where you could enter the mirror image mission multiple times, I can't tell you how it was done due to were I got the information from(aka NDA), it's being fixed.
He couldn't kill the mirror so I got on to do it for him, died, then chaos storm killed the mirror. It gave me the exp but took me back to augury so I had to do it again. Pretty cool I guess.