In The Modern Times, I purchased a new airplane and immediately assigned it a twice daily Athens - Ljublijana flight. Thus, the route already appeared on the Route image page, however, it appeared twice (see screenshot attached). The same happened with another new flight that I scheduled twice daily and haven't operated before.
The flight is not operational so I don't know if the two entries will merge once the airplane is delivered and the flights commence but even now I don't think the same route should appear twice as (if I understand correctly), there is only one route image per city pair and not different ones for different flights.