Goliaths triple the XP of their kills, so what if one Goliath kills another?

I read recently that Goliaths receive triple the XP of each enemy they kill. Makes perfect sense.

But I was letting one Goliath level up in Tundra Express (being slowly weakened by Mordecai’s Slag Rifle), and it was killed by another Goliath. I didn’t get a chance to check the XP when I then killed the the remaining Goliath, but does anyone know if it will stack, and multiply the total of the levelled Goliath again? And if so, does that Goliath need to be enraged for the triplication, or will it still count if he’s simply an “Enemy” defending himself?