This is unique as far as I can see, I am looking forward to seeing how the 20MB fork plays out largely as the first real test of how well "voluntary consensus" works in practice.
200 years ago the very idea of trying democracy was considered a "grand experiment" (one that many predicted would fail). Today "voluntary consensus" is the grand experiment.
I'm sure that like most experiments, the very first time it is attempted it will be a total mess and many people will run around proclaiming that it can never work.
Choosing new names for at least one of the forks is going to be messy. How about a BIP that deterministically chooses names based on the first block on each side of the fork?