Domain pointed on my IP Failover

Hello, I have WHM Cpanel, and i add few IP Failover on my server. Each IP failover host only one domain. On one of my IP failover, i see some domains name pointed on it. Those website which are not mine duplicate my website on this IP failover. How i could do with WHM to only allow my domain to my IP failover ? I heard normally, it's something by default with WHM, it's make a 404 to others domains pointed on IP of your server, but not this time. I'm really confused and i dont known what to do. Could you help me please ? Cheers