They don’t appear to be alts based on login records, but regardless, intentional collaboration in the Arena is considered cheating. Since they have not made prior offense and may not be aware of this (though it should be obvious to most players), I have sent a warning message to TNT requesting him to stop immediate or he will be banned. Furthermore, his tournament prize winnings will be confiscated.
Now this is made fairly clear on this thread collaboration=cheating. Do expect the next set of players who intentionally collaborate on arena ranking to be banned without any warnings.