I would say pure coincidence, how ever sometime we tend to use the aircraft an the same routes, in the summer we used G-CELI and G-CELJ on alternate days on this:
MAN-EDI-MAN-BUD-MAN-AMS-MAN-IBZ-MAN
that was the aircrafts rotation for the day, with some small breaks in between.
unless EZY where doing the same for a while??