I let a buddy load 45 Colt once - load was 14 gr Blue Dot. It was his first time loading on a progressive. I weighed all one hundred rounds when he was done - one weighed about 14 more than the others. I pulled it apart and sure enough, 28 grains of blue dot in there. That probably would have been enough to blow up a large frame Blackhawk. Very lucky I caught that one. That was on a Hornady LNL with auto-index. I think it happened when he was going 1 at a time to get the powder measure dialed in. He must have pulled the case out to weigh the charge and put it back in the shell plate one position behind so it got charged twice. Again very lucky.
The OP's pictures also show how valuable wearing protective eyewear can be.