Automated checking for duplicate IP addresses

[mizzao]

For the future, to minimize smurfing from when one person joins synchronous games from multiple accounts. IP tracking is currently turned on but we don't really do much with it other than record it.

Smurfing happens rarely, in my experience. Sometimes this is legit when it's actually two people behind the same NAT, but usually we want to be able to investigate and see what is going on.

Worst case smurfing that's happened to me is when 25 accounts from India did the same HIT consecutively, but that was in 2011 and I haven't seen it since Amazon clamped down on identity tracking.