As alluded in the latest How its played video, "When Do You Declare Nimble Dodge?", there are two reactions in the system called "Nimble Dodge" with the same effect. These only differ in the specifics of its trigger, as the player and Derro option triggers when targeted, and the Drow option triggers when hit. That difference even seems hard to discern to some which enhances the confusion.
To address this, I simply suggest a new name for the less common ability (Perhaps "Trick dodge" for the Drow?). This of course, unless a designer is interested in making them the same to match a predetermined intent.
There are also two features called "Reckless Abandon" (this time different), one for the barbarian and the other for the Goblin ancestry, for which I would suggest the same.
Past posts alluding to the two "Nimble Dodge" and its triggers: