Do you have a single solution in VS2019 that contains a configuration to compile the code for VS2017 with SDK 6 and another configuration to compile it for VS2019 with SDK 7?
Or do you have two separate solutions (one in VS2017 and another in VS2019) referencing the same code?
If you are using GitHub, you might consider just creating separate branches for Rhino 6 and Rhino 7 builds. This way, you don’t need to add additional build configurations.