Creating multiple datapack dimensions which reference the same dimension_type string causes "The game crashed whilst exception in server tick loop
Error: java.lang.IllegalStateException: Unregistered dimension type:" crash upon world creation.

If I create separate dimension_type JSON files for each dimension I create (which are copies of each other apart from the file name) and link each dimension to a uniquely named one, world creation will complete successfully and the overworld will load; however, entering one of those custom dimensions (let's say dimension A) causes a lot of lag followed by an eventual nondescript crash.

If I remove all dimensions but dimension_A.json and all dimension_types but dimension_type_A.json from my datapack and create a new world with it, the world loads fine and runs normally without crashes.