There's already a significant level of confusion between the two products. The decision to change will not get any easier and the impact of a name change will only increase as you drag on. You should change it now because there's nothing gained by waiting.

Fwiw, ZURB's Orbit was my first thought too, and mattdeboard is right that changing the name will only get harder not easier.

That said, it's probably also the case that most of us will just make note of the fact that there are two Orbit.js's now and qualify which one we're referring to when needed.