Suppose I have both Kor Spiritdancer and Mesa Enchantress under my control. They have two similar abilities:
Kor Spiritdancer: Whenever you cast an Aura spell, you may draw a card.
Mesa Enchantress: Whenever you cast an enchantment spell, you may draw a card.
If I now cast an Enchantment — Aura card, do I draw two cards or one?