it's possible that the PostgreSQL will be listen to different IP addresses. Means, two different odoo server (with different IPs) can call the same Postgresql server(this might have its own IP as well).
odoo server 1(192.168.0.1) ----->
Postgresql server (hosted on another ip)
odoo server 2(192, 168,0.2) ----->
Actually our requirement is we need configure one central database which is connect with two instance separately for separate IP
Possible