I have recently attempted to get rid of my two nameservers on two different boxes and temporarily set them both up on one box.

This has involved changing both the IP addresses of the nameservers to xxx.xxx.xxx.xxx. Doing a dnsreport.com shows this error:

ns2.xxxxxxxxx.biz.:
Parent server (h.gtld.biz) says A record is (new ip of ns2), but
authoritative DNS server (new ip of ns1) says it is (old ip of ns2)
ns1.xxxxxxxxx.biz.: Parent server (h.gtld.biz) says A record is (old ip of ns2), but
authoritative DNS server (new ip of ns1) says it is (old ip of ns1)
ns1.xxxxxxxxx.biz.:
Parent server (h.gtld.biz) says A record is (old ip of ns1), but
authoritative DNS server (new ip of ns2) says it is (old ip of ns1)
ns2.xxxxxxxxx.biz.:
Parent server (h.gtld.biz) says A record is (old ip of ns2), but
authoritative DNS server (new ip of ns2) says it is (old ip of ns2)


The server was clustered with the other three during transitition and is right now. I removed the nameservers on the other two boxes though. Why would my new nameservers be reporting the old ones?

At the moment people are having trouble accessing sites and one user's mail is bouncing to legit addresses.

In the same way you originally created your name servers at your domain registrar, you need to update your name servers IP's at your registrar as well. That way your new name server IP's gets into the root registry.