Khiona or Domitia?

While the “different symbols stack” is a convenient general way to explain stacking, it’s actually wrong in this case. All variants of attack buffs from hero specials are non-stackable; the only exception are those with different mechanics, namely Gambler’s Stance (Wu Kong) and Martial Prowess (Tarlak).

There are several places on the forum that discuss this, here are two convenient ones: