1. Running loco joins on the same track behind the train as it enters the station. It couples with the train while running at a slow speed (like you see in so many movies). When the train stops, the leading loco disengages and then loco at the back starts pulling away.
2. Loco is already attached to the end of the rake. At the station, the earlier leading loco just disengages and the loco at the back starts pulling away.
3. Same as number 2 above except that leading loco does not disengage....
more...

This would be useful for trains which have multiple reversals en route.
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Dont take the above 3 possibilities seriously. I just answered your 'how' question :) In reality, your data source needs to be updated since 2 mins is incorrect if there is a loco reversal at the said station.