Hi, is it possible to use one physical server, with 2 ips assigned to it, as 2 different DNS for my domains?

Lets supose that i have the domain testing.com

The Nameservers of the domain testing.com are:

NS1.myservers.com
NS2.myservers.com
NS3.myservers.com

But NS1 and NS2 are the same server.

Is this possible to do? and if it is... how can it be done?

It should be possible, as you stated yourself, you just need 2 IP numbers that point to the same computer.
On the other hand, the idea with several DNSs, is that if one does not answer (offline, server down, busy etc.), the next in line will be used, so it will increase the time it takes for anybody to look up record on the domains you host (worst case scenario).

All it takes is to set up in your router/firewall, that traffic on port 53 (udp) to these IP numbers should go to the same internal IP number (or simply add another IP number to the NIC, depending on the security you have).

regards,
J.

Thanks Json already do it and working