Awesome capture!
I can analyse the reason because:
Passenger and KCG SBC had stops, so they stopped!
From Raajdhani's side, previous station is 7 Kms away, whereas from MYS SNSI, previous station was 12 kms away!
both...
more... the trains must have crossed these stations same time, but as rajdhani just have to travel 7 kms to DBU, it reached first and was made to stop!
Meanwhile MYS SNSI had no station enroute of 12kms so it cant stop in middle, and hence rajdhani stopped and MYS SNSi was given green signal!!!