I want to run two websites on ONE apache installation running on Debian. I want both of my sites to be on port 80. They are both assigned to two different DNS records. When 123.456.78.901:80 is accessed from www.mcpvp.net, I want it to go to Site A. When 123.456.78.901:80 is accessed from www.pmcpvp.net, I want it to go to Site B.
You need to use apache VirtualHost in order to redirect traffic coming from certain DNS records to certain folders on your server.
DigitalOcean's tutorial explains it well: https://www.digitalocean.com/community/tutorials/how-to-set-up-apache-virtual-hosts-on-debian-8