All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
The problem which you mentioned could be solved by undertaking the following steps:
1) You and whoever knows these two men should endeavour to reconcile between them and solve the disputes between them. Reconciling between people is one of the best acts of worship by which one seeks to get closer to Allaah. Allaah Says (what means): {No good is there in much of their private conversation, except for those who enjoin charity or that which is right or conciliation between people. And whoever does that seeking means to the approval of Allaah — then We are going to give him a great reward.}[Quran 4:114] Reconciling between the two disputing parties should be by reminding them with the seriousness of injustice and urging them to forgive each other. One should convey to each of them the good that the other says about him. Even if one lies to them by conveying something good from one side to the other despite them not having said so with the purpose of reconciling between them, he would not be sinful as confirmed in the Sunnah. For more benefit, please refer to Fatwa 84728.
2) Reminding the person who is wrong by the seriousness of his injustice in this world and in the Hereafter, and urging him to repent to Allaah and to do good, perhaps he would repent.
3) Urging the wronged person to forgive and reconcile with the person who wronged him, and to forget what the other person has done, as this is one of the characteristics of the believers. He should also be urged to seek forgiveness and repent to Allaah, as committing sins may be the reason why this man treats him unjustly. One of the pious predecessors said: “When I sin, I find the consequences of sinning in the conduct of my wife and my sumpter.”
Allaah Knows best.