Diti is named only a handful of times in the Rigveda, always in formulaic proximity to Aditi, with no hymn, no epithet and no story of her own. A figure of that antiquity with that little attached to her is unusual, and her full career begins only when the Puranic genealogists need two mothers.
What would resolve this Comparative Indo-Iranian evidence for an independent figure behind the abstract noun, or a demonstration that the Vedic occurrences are all secondary to the divine name Aditi.
OpenVedic philology and comparative Indo-Iranian linguisticsArthur Anthony Macdonell, Vedic Mythology