Aunt Kellee sent these a few weeks before the boys were born. After 20+ ultrasounds each was differentiated by the label "A" & "B." . "A" most always had his hands covering his face. "B" was a thumbsucker and kicked quite a bit more. And then when they were born it was, A & B until we got the name thing sorted a day later.
So here we have it. "A" became Charles & "B" is Clyde.