IP and pvp rank list

Hi to all,
i am working on my pvp rank list and realized that many people kill their alts to get higher rank in the list.....
So i tought to put an ip linked with their accounts. Currently in the registration form the ip is taken everytime someone register...( older players didnt register with this script so they miss the field of ip)
the problem is that many people use dynamic ip and that isnt good at all as u can imagine...
my idea is to add an ip field to roles and when they vote it stores the ip then i check the account that killed and the one that died and if they have the same ip they get banned from the pvp rank...
this method has too many faults if u think about a person that first votes then change ip and then starts to play....
the best thing would be somehow to add the ip field so that it takes it when they login in the game and puts it in a table that later i will check and so on
i would like to ask any kind of advice about this matter
thanks to all for any advice or idea :)

I stopped bothering with it since there are many ppl on my server that are playing from same IP, they would just share their kills, I just got warning message over my PvP table that if you are reported as an alt killer, you are banned from ranking and it works.

The best solution is best in the logs:

But I'll help.

// Other Limit Good Cultiv >=7 for join in Rank PVP
DELETE FROM pvpselect;
INSERT INTO pvpselect (idpego) SELECT DISTINCT morreu FROM pvp LEFT JOIN users_shadow ON pvp.morreu = users_shadow.roleid WHERE level2 <8;


"SELECT atacante,DATE(y1) AS dia, count(morreu) AS resultado,morreu FROM pvp WHERE y1 >= (CURRENT_TIMESTAMP - INTERVAL 30 DAY) GROUP BY atacante, morreu, dia HAVING resultado >15 ORDER BY resultado DESC";"

If the person killed more than 15 times on the same day the same person
On my server eg: I take the points that the person gave to the other

But I gave up looking for a way to get filtered because player is a difficult thing.
And we have to make a few variables, very bad idea to use IP, Mysql table would get giant lag out in the consultations that would give

i like your idea zdark i think is the best and easiest way to manage it :)