Just name them, what are they going to do to you?. Oh look the Blizzard police are here. Get banned for speaking and telling the truth, stuff them and the brown nose’s can get stuffed as well.
It is really very important to indicate the hero that the opponent you are talking about had because there is a companion + the heroic power that copies the servant that we have in our left hand (and this can easily explain several triple copies of the same servant).
But if you are sure someone is cheating, why not report it in-game ?