Amritsar Jan Seva Express: हम मजदूर है साहब! - Piyush Singh

What I came to know was that 12617/8 Mangala Lakshadweep express is the descendant of this Jayanti Janata express. But it wasn't a direct descendant though. Lot of changes happened in due course, before today's Mangala Lakshadweep came into picture.
1973/4: 131/2 Delhi Nizamuddin – Mangalore/ Cochin (Jayanti) Janata Express (splitting/joining at Shoranur) and 17/18 daily Madras – Delhi Janata Express were started.
131/2 was initially bi weekly, then tri weekly and later 5 days a week. 17/8 was daily since inception and was extended to JAT somewhere around the introduction of TN....
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1988: Big 4 of south became daily. During same time, Janatas were discontinued and were converted to standard express.
When Kerala became daily, 131/2 service was discontinued and was merged with Kerala and for very short time, Kerala ran as Kerala-Mangala express with splitting/joining at Shoranur(Kerala part towards TVC and Mangala part towards Mangaluru).
At the same time 17/18 MAS – JAT Janata was converted, split and extended into three trains in 1988, the Andaman (MAS – JAT), Himasagar (CAPE – JAT) and Navyug (MAQ – JAT) Expresses of today. Now till SVDK.
Don't know when and why the slip portion was discontinued.
1998: With opening of Konkan line, the lost connectivity of Mangaluru was restored with 12617/8 Mangala Lakshadweep express running till ERS.
Not just these 2 trains, but other JJ category trains introduced during 1973/4 period are now running as some or the other train.

Thanks for the info.
1. Another IRFCA account too says what you said click here that 2 JJ were started in 1972. One of which is now Mangala.
2. Another description calls it "Kerala Mangala Express" - "The Kerala Exp. overlapped with the Jayanti Janata which bifurcated at Shoranur with one part of the train going to Cochin Harbour and the other to Mangalore. Later, these two trains were merged to form the Kerala Mangala Exp." click here
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I thought Mangala was started in 1993 after seeing this click here
4. Here is an article but not much info click here A pic too is seen, but not sure if it was of Jayanti Janata's.