Not a bug per say as I believe this was done deliberately at some point to ensure that servers get run. But should be changed.
is hardcoded to work with only 2 servers (1 master and 1 shard that are named '/Caves/' and '/Master/'). As a fellow developer I have gone trough fair length to try to get info on the function in question and finally decided to decompile your exe ( do not ban me ;P) To find out the server config generation has been hardcoded as well as launching the servers. This is bad design as far as I understand you are providing us with options to mod and this is hindering ability to mod a big aspect of the game. If it would be lua function it would be easy as we can change stuff there but this function stems from C++ and cannot be even viewed properly.
I have also listed some steps I have tried to bypass it in forum thread
Try all the possible ways how to launch a third server from client via modding.