Multi-accounter / Playing horde and ally char at same time.

Hello.
Hope this isn't the wrong forum.
Today (Wednesday, 10th June at about 20:40) I wanted to farm in Windshear Mine (in Stonetalon Mountains) and encountered a high level gnome Rogue together with a level 24 or something Orc Warlock who were (together) pulling together many mobs in the mine and the warlock would then kill them. More annoyingly, the rogue killed all horde characters in the surroundings so the warlock would have all the kills to himself. This seemed suspicious, and surely enough the Warlock admitted to being the rogue on an alternative account. This is seen in the following screenshots (the nightmare guy is the warlock in question, I do not remember the name of the gnome, unfortunately):

(see chat in lower left where I warn another player to not go into the mine)

Needless to say the chat doesn't end there. I was quite angry and told him I would report it and hope he gets banned. He quickly backpedaled saying things like "link me to where it says this isn't allowed" and "I never admitted to anything" and similar things.
It's possible that this is behavior is allowed on this server, but I wanted to report it just in case.
Also let me know if I can help with any kind of further evidence.
Hope this isn't the wrong forum.
Today (Wednesday, 10th June at about 20:40) I wanted to farm in Windshear Mine (in Stonetalon Mountains) and encountered a high level gnome Rogue together with a level 24 or something Orc Warlock who were (together) pulling together many mobs in the mine and the warlock would then kill them. More annoyingly, the rogue killed all horde characters in the surroundings so the warlock would have all the kills to himself. This seemed suspicious, and surely enough the Warlock admitted to being the rogue on an alternative account. This is seen in the following screenshots (the nightmare guy is the warlock in question, I do not remember the name of the gnome, unfortunately):

(see chat in lower left where I warn another player to not go into the mine)

Needless to say the chat doesn't end there. I was quite angry and told him I would report it and hope he gets banned. He quickly backpedaled saying things like "link me to where it says this isn't allowed" and "I never admitted to anything" and similar things.
It's possible that this is behavior is allowed on this server, but I wanted to report it just in case.
Also let me know if I can help with any kind of further evidence.