I think the key term is USED.
Replace with a brand new one.

Paul Guzyk <paullist@GUZYK.COM> wrote: I'm helping a fellow listee.  His 87 Westy had no spark, we
determined the coil was bad so we replaced it with a good used one.

A week later same problem, installed another used coil to fix problem.

He's running now, but I'm concerned, is there anything that could be
causing the coils to die prematurely?

BTW, he does not leave his ignition key on without engine running
(radio is hot all the time).