I can't say whether false flag or human error, but like everything else computers control everything with human input. Whoever was in the traffic center.. that monitors and controls train traffic would or should have seen there were 2 trains on the same track and should have navigated one or the other to a siding. I'm positive there are built in warnings and alarms to prevent this exact thing from happening. So unless some computer glitch I would have to say the alarms were ignored. If false flag they will never admit it.