I log IP addresses of who entered the username. If it doesn't match an IP used with that board account, it won't be counted as a valid entry... i.e. if you entered my username in the form, it will list your IP with my username. I can verify if the IP is valid for my username. If it isn't, it won't be considered a valid entry and I'll just remove that entry from the contest.
The things that I've loved the things that I've lost
The things I've held sacred that I've dropped
I won't lie no more you can bet
I don't want to learn what I'll need to forget
- Audioslave, "Doesn't Remind Me"