-ㄴ지 turns a clause into an embedded question and 헷갈리다 means getting mixed up between things. Five of these lines set two such clauses side by side — A인지 B인지 헷갈리다 — which is the classic shape: 여기가 대낮인지 밤인지 헷갈려 (I can't tell whether it's midday or night). With a single clause it means simply not being sure of the answer (누군지 헷갈렸어, I got confused about who it was).