When the duplicates were formed by importing the already present folder, the debug did produce this error:
[_LOG_LEVEL_FATAL 21:22:56.020289] noise_library_manager_add_folder_to_library: assertion `folder != NULL' failed
[_LOG_LEVEL_FATAL 21:22:56.020311] Noise will not function properly.
When the duplicates were formed by importing the already present folder, the debug did produce this error:
[_LOG_LEVEL_FATAL 21:22:56.020289] noise_library_ manager_ add_folder_ to_library: assertion `folder != NULL' failed
[_LOG_LEVEL_FATAL 21:22:56.020311] Noise will not function properly.
I'm not sure if it's relevant or not.