I've actually seen more evidence to the contrary. Shadows talked about the music she liked, and Metric (or anything like them) was never mentioned, nor did Shadows have anything to do with Canada. In addition, Sugar's "attention-seeking" posts (which for the most part seem to actually be normal posts made by a user that presents themselves as female) are nothing like Shadow's. If it's the same person, they're completely different acts except for the gender.