रेलफैनों की तो बात ही कुछ और है

Recently I booked one ticket in 3A for 2 passenger for NDLS to LDH. Before booking it was showing available 1, hence I thought that ticket for first passenger will confirm and for second passenger it would be RAC. But to my surprise - got one confirm ticket and second on PQWL 20, not even RAC. I am not able to understand or digest serial number 20 for second passenger.

Can some expert explain this logic?

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