sir upto delhi srai rohila it is double...after that its single line and i have checked this thing personaly coz i was travelling in ,mandore every month since last one year and mandore is always allowed to halt at dee for shatabdi and i have seen that the track at which ajmer shtabdi had passed, the same track is used by mandore also after the clearence..
acyualy the other tracks coming from ndls towards dee are used by the trains going towards ambala side...