Question about Kingdom of Heaven

Hi. I've been watching this movie over and over again. There's one dialogue that doesn't make sense to me.

When Balian is defeated at Kerak, Nasir says "Your quality will be known among your enemies, before ever you meet them." Then Balian says "You are not that man's servant."

Nasir replies "No, he was my servant."

At the scene where Balian fights and kills the cavalier for the horse (43:00), the servant isn't Nasir. He doesn't look like Nasir. Compare the faces at the scene where Balian says "Take the horse (part 1 46:25) and the scene where Nasir explains who defends (part 2 56:17). They are two different people.

If the servant to the cavalier was Nasir, the scene fighting for the horse didn't make sense either because the relationship shown by the two muslim men definitely indicated the cavalier was the superior. Would it make sense for them to reverse their roles before confronting Balien?

I guess I don't really understand your question and it appears you kind of answered it yourself.

Balian kills the servant to Nasir and later gives the horse to Nasir. You say that later it is not Nasir who is explaining who is defending in the Muslim camp? Not true. It is the same man.

It was Nasir's servant that Balian kills in the desert but perhaps you were confused because Nasir just appeared to be the servant when in fact he was the true cavalier.

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We are both the source of the problem and the solution, yet we do not see ourselves in this light...

Thanks for responding.

The servant explains to Balian the man he killed was a great cavalier named "Mummad al Fais". If Mummad al Fais is actually the servant, why would they trade roles when they confronted Balian over the horse?

I say the servant isn't Nasir because they don't look alike. I referenced two scenes in which their faces were clearly shown and they don't look alike. The servant has narrower eyes and Nasir has a rounder nose.

Could it be they were three people? Nasir, the servant, Mummad al Fais who is Nasir's servant?