Reading with the 22 'pink' route run by Reading Buses Monday to Saturday and as a 40C ran by Thames Travel on Sundays. Both start in the town centre and end up in Caversham
Evening and / or Sunday service operated on council tender by a different operator used to be fairly common (although not always helpful to passengers in terms of ticket acceptance and availability of timetables, unless the county council took responsibility for roadside information.) I guess tendered evening / Sunday services are less common now than they were a while ago, as are small operators who will go for anything tendered.
I can't remember the detail now, but remember one route in North Staffordshire - must have been early 90s - where the main commercial service was Potteries (PMT), and there were separate county council contracts for the weekday evening service, Sunday service, and a couple of round trips early on Saturdays. Each of those was a different operator - from memory, Midland Red North and Bakers (Biddulph) were two, but I can't remember the third.
In terms of now, Luton has Centrebus route 10 and Arriva route 27 between Luton Town Centre and Marsh Farm, although they don't follow the same route between the two.