If I'm going to post, say 6 pictures and get into the directory where they're stored and select them by CTRL + click so they are all listed in the selection box before I click the OK button, they'll all be added to the post and show as 1 download. If I need to change the display order, that can add to the count for the ones being moved. If I add the six pictures by selecting one, hitting submit, adding another and hitting submit, and do that for all six, then the first pic will have 6 downloads, second will have 5, and so on until the last pic will have only one download.

Just what I've observed and I have no other knowledge of what's really happening so I could be mistaken.