Both WAP5 (Bo-Bo) and WDP4 (Bo1-1Bo) are high speed locos. But WAP5 loco has a higher output vis-a-vis WDP4 loco. A WDP4 can achieve 160 km/h only with 10 coaches (485 tons) on level.
So, WAP5 loco is preferable for Bhopal Shatabdi which consists of 18 coaches (880 tons).
Personally, I think N.Rly should use a particular WAP5 (# 30086) with this train as it can deliver a marginally better performance than other P5s at higher speeds.