As I said in another comment, I'm pretty sure "same millisecond" is being used by the photographer in the sense of "same instant" or "same moment in time" not literally same millisecond based on a super-accurate time source. That information does not exist in the photo's EXIF data which is one-second resolution and typically derives from a manual time/date setting in the camera's menu.
I am not taking issue with the author of the post as I agree, that is likely the intent. But folks here seem to be parroting it as fact rather than taking the liberty you and I seemed to do.
