In the full game I had this same thing happen to me, I picked Big Daddy in a recent match and it gave me Sly Cooper, did anyone else get this?
I'm getting this bug alot too. I'm also getting several other glitches that are literally driving me insane. I get the "different character" bug when I connect to a match, it doesn't start, then I reconnect to another match...that's when it swtiches my character. I'm also getting a bug where I won't respawn after death for about 45 secs. Making it impossible to score. There's also some issues with lag, I'm not sure if that's what it is, but characters will be right in front of me one second, the next they halfway across the screen.
I'm so in love with this game, but I can't play it at all with all these dang glitches. PLEASE fix it!