The station of Nagpur is being shared between C.Rly & S.E.C.Rly.
2 different station codes are being used by railway administrative for Nagpur are :
NGP - C.Rly
NAG - S.E.C.Rly (which is rarely used)
Attached...
more... image is for the actual location where administrative zone changes which is nearly 500 mtrs away from station (CSTM-HWH section).