I understand that Leeds trams did similar, only more so, in that most tram journeys ran across the city centre, and each route number always went with a particular terminus, so (for example) a tram to Lawnswood would always show '1 Lawnswood' irrespective of what south Leeds terminus it had started from. On arrival at Lawnswood, it would show the number for whatever south Leeds terminus it was going to next.
I don't know enough about the system to know if specific pairs of termini were always linked, or if this varied by time of day / week.
Trams terminating in the city centre tended either not to show a route number, or the route number blind was deliberately set between two numbers to make it stand out. (I remember seeing one tram crew at Crich do this on their last journey of the day with a Leeds tram.)
I'd forgotten about that. Thinking about it, the Docklands Light Railway also had colour codes for the original two routes (Island Gardens to Tower Gateway or Stratford) photo (not mine)
here.