A push pull passenger is a passenger that has two locomotives, one at the front and one at the back.
Naturally the front loco does the pulling and the back loco the pushing.
The loco pilot is usually in the first loco and the trailing loco is remotely controlled..
Care is taken to maintain higher tractive power at the pulling loco than...
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at the pushing ones, as otherwise the passenger coaches may derail..
Care has also be taken to use two locos of the same make and same build and same ratings as well.
The primary advantage of a push pull passenger is that the train can immediately start of from a terminal without worrying about a loco reversal.
Furthermore Hyderabad is 500m above sea level, right at the centre of the deccan plateau.
There is a considerable elevation change in the 150kms from Warangal to Hyderabad.
Using two locos means lower powered locos can also be used....
Actually thess are the legacy of IR's earlier days, when powerful locos were scarce....
Hope this helps!