I sent Mike Diamond an email and here is his answer.
Hi Richard. It looks like an authentic tapered planchet error. I'm not sure if there's a straight clip or if the fragile thin edge was simply damaged. I don't know what caused the pits. Mike In a message dated 3/13/2018 1:19:49 PM Central Standard Time
Always nice to get a review from Mike. Thanks for sending that along and posting his response as I like my coins to have accurate labels and they don't get more accurate than that. In hand it really does look like a straight clip, especially edge-on, so for now I'm keeping that on the label. I agree it would be hard to be sure from the pics I posted.