A couple of years ago I saw GWR operate 3 x 153s on the Devon metro with differing liveries; one was Casper ‘white’ livery, one was GWR green and one was FGW plain blue.
Three liveries on the same train service has been fairly common on GWR up until a couple of years ago, on summer Weymouth runs you’d see 5 coach formations formed of GWR green, FGW local lines and FGW plain blue.
For a while it looked odd when units worked together and you got the same livery throughout!
Come to think of it, The West Fleet also had a varied patch where you could find the Sprinters in an number of liveries too, all working FGW Services around 2010/2011:
London Midland 153 / FGW Local Lines
London Midland 153 / Local Lines 150 / Plain Blue 150
London Midland 153 / Local Lines 150 / Plain Blue 150
London Midland 153 / ATW 150 / Silverlink 150 - (had to be one of the strangest combinations of the all!)
ATW 150 / Silverlink 150
ATW / Local Lines
ATW / Plain Blue
Silverlink / Local Lines
Silverlink Plain Blue
Central Trains / ATW
Central Trains / London Midland
Central Trains / Local Lines
Central Trains / Plain Blue