हम हवाई जहाज़ उड़ाने वाले, फिर भी फ़िदा हैं, पटरी में दौड़ने वालों पे. - SK Mangla

It's there used by few daily commuters using local suburban trians.
@ eg. For Borivali to Chruchgate .. those passengers commute in the rush hours and hence expect least checking in train compartments while on train journey. And hence they buy two railway passes - one for Borivali to Malad and second from Grant Road to Churchgate. This is instead of buying one full pass from Borivali to Churchgate.
@ The same operandi by those few Virar-Churchgate commuters - buying of two passes - one from Virar to Vasai Rd and...
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second one from Grant Road to Churchgate.
@ This is the modus operandi for such commuters and off the record it's known as Nylon pass holders.

I am not aware of these passess but yet what Mr. Kapadia has informed, the benefit can logically be explained as follows:
Suppose a commuter travels between station A and station Z where B, C, D.....W, X and Y stations are in between.
Season Ticket Fare structure-
1. A to Z Rs. 100
2....
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A to B Rs. 30
3. Y to Z Rs. 35
Now if one takes ST nos. 2 and 3, he is spending Rs. 65 and he is valid ST holder at Platforms and entry/exits at A as well as Z while for direct ST, he had to pay Rs. 100.
I would, without being required for, request fellow bloggers not to spread this feature as it is not only risky meanwhile but also illegal.

Contd.
@ This is info... just for the know of the bloggers and no question of any spreading of this system which has also been in notice by the Mumbai Suburban Railway officials. This nylon pass modus operandi was also reported recently in one Mumbai newspaper also.
@ Note that .... There is nothing wrong and it's perfectly offcial in buying two passes as outlined above but it may also be noted that one is travelling at own risk of being caught at in between stations where one holds no...
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ticket/pass to travel.
@ Those using such twin passes- know the consequences of catching at in between stations but they are knowingly doing this. Everybody knows that travelling without proper ticket is illegal and subject to fine and prosecution if caught by TC /TTE.
@ This is eye opener for those taking undue benefit by adopting unfair means and practices. Also for those on the way. It's for the Rlys to check out this menace at the earliest by strenghtening task force even during peak hours.
Good wishes.