As per IRFCA's old train number archive, this is the evolution of Netravati Express (Check link: click here
OLD NUMBER TRAIN DETAILS NUMBER IN OCT,1988 PRESENT NUMBER COMMENTS / PRESENT STATUS
935/936 BB-CHTS NETRAVATI EXPRESS 2135/2136 6345/6346 ...
more... LTT-TVC NETRAVATI EXPRESS
957/958 DR-MAQ EXPRESS 6657/6658 --- --- --- Got merged with 6635/6636 NETRAVATI EXPRESS
AFAIK, 2135/36 ran as tri weekly & 6657/58 was a bi weekly(which means MAQ had DR service just twice a week, whereas CHTS - BBVT ran thrice a week). After the Konkan Railway line got operational in 1998, both the trains were merged into a daily service connecting TVC with LTT via ERS, SRR, KNKD, MAO).
In reality, MAQ (MAJN rather) got daily connectivity to LTT when a tri weekly plying between CHTS & BBVT and a bi weekly to DR(which originally belonged to MAQ) got merged in 1998. So fail to understand who stole what!!