In their paper the example is servers sitting behind a switch which respond to ARP requests for the same IP (in addition to their own IP) which allows packets f

In their paper the example is servers sitting behind a switch which respond to ARP requests for the same IP (in addition to their own IP) which allows packets for that shared IP to reach both servers (2 in their example). The servers accept every 2nd connection + any established+related connection packets. All other packets are dropped.