It means the mod is sharing the same class as the minis. Try giving the F1 1982 mod a new class; open the .veh file of each car in the mod and find the line Classes="reiza#" add a comma and add another class
The mod you have converted has its classes as reiza5 (the mini's). You will need to change it in the .veh file. this is the entry you will need to change.
e.g Classes="reiza5,F1-82"
You may need to create your own section, this should help.