I have noticed that is not possible to create a Virtual Driver for more than one series. For example, if I want Scott Pruett to race in both NASCAR and Sports Cars, rF2 will only recognize the Virtual Driver that was created first. The only way I can have the same Virtual Driver in more than one class/series/car, I have to make his/her name something like "ScottPruett" or "Scott Pruitt" or "S Pruett", but I cannot use the name "Scott Pruett" again. I'm not sure how tricky a fix would be, but I use Virtual Drivers almost exclusively (I'm sorry I won't race Frank Tankslapper) and it limits the whole idea of the feature in the first place. I have noticed this also becomes an issue if there is a mod installed with that driver's name. So if I were to install a mod with Scott Pruett, my Virtual Driver would disappear.
I have this same issue. I use literary giants (Hemingway, Melville, et. al.) as drivers in my 1991 offline series as well as in a 1966 series. I had to put two spaces between the first and last names in the 1966 series to make them work in both places. That also meant I needed to copy/rename the driver sound files in Spotter2. I've noted that the instructions for creating AI say the name has to be unique, but when I first read that I didn't think it meant unique across the whole game.