Overlapping or nested slurs must be drawn at different heights to avoid visual collision

When two slurs share some notes (nested or genuinely overlapping without full containment), the outer/later slur must curve further from the staff so the two arcs don't touch or cross.

Gould ('Overlapping slurs') and Ross ch.12 both specify nested/nearby slurs are engraved at increasing distances from the noteheads.

This rule needs the notated content and the rendered result together — the score says what should happen, the page says whether it did.