I witnessed first-hand from more than one of these boomerang employees, moralising to their colleagues about how they too should leave as they were worth more, and they themselves wouldn't tolerate any more disrespect from management.
I know there were different reasons for leaving in the first place, so not putting all the boomerang employees in the same category, but all I am saying is you better have your narrative sorted about why you have returned, because I will ask when I see you and please spare me the bullcrap, because you have returned on inferior conditions to previously when you factor in seniority for staff travel and rostering.