This train belongs to SER and here 12817/18 and 12873/74 are distinguished via BKSC and via BRKA as both are the nearest major stations on different routes.
People hardly know about Chopan which does not even lie within the state of Jharkhand after which the train has been named.
I request to let it be via BRKA which is appropriate else if I go by your logic then-
via...
more... Chopan does not tell us about the further route it will take ....via CPU-ALD-CNB or via CPU-ALD-LKO-MB- or via CPU-MGS-LKO-MB....there are many possibilities beyond CPU also so let it be BRKA which is used by people here to distinguish rather than CPU.
Thank You.