Admin's response:
Hi,
That's a very good question. It's never allowed to have the same exact player twice on a team, and to my knowledge it's never happened. It must have been some kind of strange glitch to make that happen.
I can replace one of them if you can provide a valid replacement player.
I will defer to ozomatli on this...it seems pointless at this time to make a change, but happy to do whatever he thinks is best.