Wow .. Who's that "Hot Friend" of yours? .. xD

Anyways, the requirements for you to be qualified to enter the Cross-Server Great Ninja Wars are (1) Must win the Local Great Ninja War and (2) Have high Group Power Ranking .. The 8 Groups from your Server Cluster who met the Requirements will automatically go for the Cross-Server Great Ninja Wars .. In some instances, if your cluster has low number of groups to qualify and take the 8 spots, the 2nd place winner with the highest Group Power Ranking will also able to join the Cross-Server Great Ninja Wars .. So it is possible that 2 groups from the same server or merged-server can go qualify for the Cross-Server Great Ninja Wars ..

Ah, "he", so nevermind .. And i think i know him, someone in discord ask the same thing as yours last time ..

Anyways, what matters for qualification are the Ranking and the Overall Group Power .. In your case, and this is only my assumption so don't take my word for it as i may wrong about this .. Your server is already merged twice, but the system or the game still picks and registers group as they were before .. I mean by 1st merged groups .. so in that case, maybe that's why them and yours got into Cross-Server Great Ninja War at the same week .. since this is the only theory or assumption i see as possible or viable for the scenario you gave ..