SQL query to find users registered with the same IP?

[-FP]

Silly stuff.

I'm giving away some stuff, and I suspect people is using multiple accounts to have more chances...

[TAMAN]

come on they cant be so dumb to register with the same ip address lol  just saying 

[-FP]

SELECT ip_address, COUNT(ip_address) AS c FROM forums_posts
WHERE topic_id = 1224
GROUP BY ip_address
HAVING c > 1;

Someone actually made 5 accounts... and many others 2 or 3, lol. It may be poeple just in the same net, but... well I'll have to check signup times and stuff.