Could be a second crew change at NGP. IRFCA gives examples of trains having crew changes at Vadodara and Valsad on the WR lines, where a crew does multiple sets in a single day by doing two short runs instead of 1 long run . A similar practice might be in place here, with a crew from BPQ doing multiple short runs between BPQ and NGP every day, and NGP based crew taking over for the relatively longer NGP-ET/BPL stretch. I'm open to correction on this, but mostly these are are usual scenarios as far as crew changes are concerned.