I caught a player named SheepMan/Sheep Man dual logging in the NCR mine. Basically he used an alt to kill my cow, the alt was killed, and his other character was waiting to come and take the loot from my cow. In the screenshot you can see that my cow was killed from the chat bar (I tried to leave the mine when I saw that he was going to kill it but he shot it before I left the mine). Also you can see his dead alt and him. Here's the screenshot:
If you don't ban him, please tell me why, since this was dual logging for the purpose of looting.