Generally the bad double rejection can be employed at any point in screening. Generally I'll weed out the obvious doubles before they get to the high quality queue, unless they're both so good, I can't decide.
If you only have one photo by the time it gets to the HQ
queue (because the other's get rejected bad double), then it's at the point it should have been anyway (with one shot uploaded - or in extremely rare cases, 2).
If this shot is rejected for reasons other than double, then it's being treated like any other shot.... just because the partnering shot was rejected prior, only for bad double means little at this point.
There are not many people out there uploading doubles. It's unfortunate that the minority who do may the long task of screening (some screeners are screening 8+ hours daily), far longer than it should be.
If after all the rejections, you beleive your shot has been fixed as per rejection reasons, then feel free to upload with a comment to screeners as to what was done to improve the shot.
(I find it useful to know that you've tried... not simply uploaded a shot for a second chance, in the hope it will hit another screener).
Respected users.... If my replies are useful, then by all means...