Not sure if the press type was mentioned, but this is one reason I like an auto indexer. To double charge, you would have to manually move at least two cases on the press; one out from the charging station, and one that was already charged back into the charging station without dumping it first.
Basically, you would have to put forth a special-kind-of-stupid effort to make it happen.
On a non-auto-index, you just have to have a brief mental lapse about what you did or didn't do.
Certainly there are times that something jams and I have to clear off the shell plate on my 650, but when that happens, the first thing I do 100% of the time is dump all the powder from all the open cases... always.
Never had a squib or double charge yet in ~130k rounds.