I see that option is a lot older than I thought (October 2014) The logic has been superseded by the logic in dedup_sources() in ide_gen, so yes, I think it can go.

34ab8524 src/python/pants/backend/project_info/tasks/ide_gen.py (Eric Ayers        2015-08-17 17:21:27 -0400 495)   def dedup_sources(cls, source_set_list):