Is there a possibility to configure a two primary dns name_servers in the same domain_name like: dns1.exmaple.com and dns2.example.com?
best regards.
Yes, that is the convention. In your example, there would be subdomain A records in the example.com DNS record:
; A records for Name Servers
ns1 IN A <IP address of ns1 server>
ns2 IN A <IP addrses of ns2 server>
Also, if you are asking whether one of them has to be a slave to another, at least with Bind, they do not. When Bind is answering DNS requests, it is basing the answers on zone files locally stored on each server. The slaving part is just for convenience, ensuring the local files on the two machines are always matched.
If both servers are configured to be primary servers, and if you always update both servers to have the same local zone files, it will work fine.