Issue: History shows duplicate check boxes

That's by design. The left checkbox compares against the right checkbox and vice verse. When certain rows are unchecked, it becomes ambiguous what you want to do if only one checkbox is available (change the left side or the right side?). So in the cases where ambiguity would be an issue, two checkboxes appear.

MediaWiki's history pages function the same way: http://en.wikipedia.org/w/index.php?...action=history

Re: uploading screenshots. If you scroll to the bottom of the page (NOT in the editor) below Quick Reply, there should be an attachments section. I'm not sure who designed the issue tracker that way, but that's where they put it.