17050/57139/17049/57140.
Ref: http://goo.gl/ULFnS
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57139 goes with 17050 till DKJ after which it runs as Passenger Train.
57140 then comes back to DKJ and runs combined with 17049 till SC.
17050/57139/17049/57140.
Ref: http://goo.gl/ULFnS
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Apparently it appears that some of the coaches of the 17049 are detached after maintenance and then it starts as 57139, comes back as 57140, coaches gets attached, it proceeds as 17050, comes back as 17049 and the cycle continues.