connection between two different lan directly

I HAVE TWO COMPUTER WITH TWO LAN CARDS.
AND I HAVE ONE ONOTHER DEVICE WITH ONLY SINGLE IP ADDRESS.
I WANT TO CREATE FULLY REDUNDANCY BETWEEN THIS DEVICE TO TWO COMPUTER.
AND IN ONE COMPUTER WE CAN NOT DEFINE SAME IP ADDRESS LIKE “192.168.0.1” AND “192.168.0.11” FOR ONE PC-1 & “192.168.0.2” AND “192.168.0.12”
FOR SECOND PC-2.
EVEN IN ONOTHER DEVICE IP IS “192.168.0.13”.
HOW IT IS POSSIBLE TWO CONNECT FOUR LANS OF TWO PCS WITH THAT DEVICE