Feels like we might have different versions of Download Helper maybe. I got 7.6.0 for Firefox 91.
Definitely can't download a second time within same session because download buttons disappear even on the right side menu. In your screenshot you have both play and download buttons after download, I just have play.
But that's probably not too relevant.
Tried the download function for new session. Yes, for duplicates I can now see the "-#" suffix before I save it, which helps, thank you. This saving prompt is slower though. Would have preferred how it works for you in your first post - Quickdownload, and if file name conflicts, then overwrite prompt. Still, this is something.