as far as I am aware the Titan aircraft have a different layout. G-POWU has 38 rows with 3 seats abreast in row 38, G-POWN has 37 rows. Thomas Cook aircraft only had 2 seats in row 38 I am sure. I may be wrong but Jet2 have just upgraded these aircraft a few days ago from 738 to A321
Seems a bit of a coincidence