I'm going to go another way. They are aware of the magical effects, but only tangentially as a theoretical manner, and find that it is completely impractical and useless. Due to the difficulty of learning about the other "kind" of magic, they both have an incorrect model of what the other magic is.
In the natural environment, Blue and Orange mana displace each other.
Drudic Blue mana users treats Orange mana events as "voids" in Blue mana, and Nomad Orange mana users treat Blue mana incidents as "voids" in Orange mana.
So Druids have limited ability to manipulate Orange mana. But the Orange mana they have learned to manipulate is only when there is a saturating Blue mana field, so it is highly inefficient.
Imagine if the only way you could see a tree was to arrange for a pile of herdbeasts to stampede through an area, and watch where they avoided the tree. From that you could ride a herdbeast and harvest the fruit of the tree.
It would be better to call the Druid's use of Orange magic as Blue-void magic, and the Nomad's use of Blue magic as Orange-void magic. This "void magic" is incredibly expensive to study or use, and produces next to no useful results for both parties, so is considered a dead end research-wise.
Both are aware that Dragons can naturally harness void magic.
Rarely, people engage in huge research projects where they produce huge mana flows and induce voids in order to capture and manipulate void magic, and get inconsistent and maddening results.
A mechanism for generating the torrents of magic required to manipulate the "void" magic could involve necromancy or human sacrifice; you first charge a human full of normal magic, then kill them to release it all at once (or produce a controlled flow through unpleasant means). That would make "void" magic dispicable and shunned.