I don't agree at all. They were clearly shot at the same time - eight bullets - IMO.
Really, I think you're dredging up silly possibilities that have no bearing on reality. There is no reason for Jeremy to go and shoot anyone again, apart from June. It doesn't matter anyway - it was just a comment.
I think you're arguing for arguing sake - there is no 'clearly' about it.
The reason for the extra shots is for staging purposes. We all have our own opinions of what happened and I believe the twins died first - receiving one shot initially.
Your original comment was that there was only two shots at the end which seems coincidental, however, that isn't the only possibility.