A Random
SCIFI.radio story

Earth develops a temporal echo across multiple timelines creating duplicates of everyone on Earth who understand us all too well even though they can all do credible singing impressions of Ethel Merman and cannot be destroyed by the army, navy, air force, space force and/or marines , but scientists create a new weapon which kills them all.
The End.
but they die from catching the common cold.
The End.