Both of them had to roll TWO saves against death, each.
Chieftain failed his first save against death.
Chieftain succeeded on his second save.
Shaman succeeded on its first save against death.
Shaman failed its second save.
In case it matters, the DC was the same on all rolls.
They both died.
If this is by design, no complaints!
But I suspect Wail of the Banshee isn't supposed to give the caster two shots at a save-or-die on each victim.
