If I understand things....
I've seen this issue since 5.9. If you DISPLAY DOCUMENT, it displays in the new application window and in most cases the browser will cache the file so you see the last (or first) document you displayed. You can overcome this if you EXPORT DOCUMENT then call the document via a URL. The document needs a new or unique file name so that you don't pull a cached file, so you have to set the file name during the export.
Alternatively, IE has a setting to avoid caching. This will work fine if you are able to just have your users make this setting change. I believe Chrome has a similar ability.