It is an overnight train for NDLS-BPL section as well as for BPL/NGP-BZA-VSKP section.
As per Dakshin Link Express fare(unable to see AP fare on IRI),
Ndls-vskp 3A direct fare = 2010
Ndls-bpl 3A fare = 1050
Bpl...
more... vskp = 1590
Ngp vskp = 1320
Since it is an overnight train there are less chances of train running empty atleast between NGP/BZA-VSKP. Instead of getting direct fare, IR preferred to get same or more fare for one seat from 2 people instead of 1 person.