The answer depends on your dominant roo. A good dominant roo will back off when the opponent shows defeat. The introduction need to be in free range where there is plenty of space to show submission. They may need to interact several times to settle who is who. It sounds like your larger roo was watching to see what the others move would be. A retreat, not a roll over is a normal submission for a rooster. Now your birds are individuals. You are watching how they interact. Is this the first time these boys have been near each other or do they have a history that could give clues about the future interactions? How far apart are their coops? Could each rooster maintain a territory with out going near the other? I have 2 free range coops. 3 roos in one 4 in the other. The two groups of roos stick to their own territories and rarely have any interaction with the other flock.