Vagary Sisters in Doom 3
At the end of Caverns Area 2 in Doom 3, you fight two Vagaries at once. I like to call them the Vagary Sisters, like how the two Barons of Hell at the end of Knee Deep in the Dead of Doom 1 are called the "Bruiser Brothers".
Luckily, the potent combination of the Soul Cube and BFG 9000 can make short work of them.