In Blender 2.80, sadly, the same limitations exist with the linking system in 2.79 (actually there are more limitations at the moment but that’s a different story).
So if you want to link multiple copies of the same rig, you can’t.
The workaround is to create a copy of the rig file, and then link in the copy as well as the original.
In the animation bootcamp files where there are the multiple rigs – they are local copies in the same file. (meaning they are not linked, they are real rigs)
You could technically link these rigs into a new file, but you will only be able to have 1 proxy of each of the rigs in that file.
Does that make sense?
I’ll record a video which explains this shortly but hopefully that is enough info to help you out right now.
