All results arrived to a SetiQueue but not sent to Berkeley is always residing under setiqueue\CLIENT
Results that has been rejected 2 or 3 times is moved to client\dublicates if doublet, or some other directory if another error. These results will not be trying to re-upload, so for all purposes setiqueue doesn't know of these.
Also, if you've set "save a copy of all results" this is on successive upload placed in client\history
So to the actual results:
In CLIENT there is 1 client.ini, log_2004-05-05.txt and older, 1 result.csv
and many pairs of result_1234 & result_1234.ini
To move all results to another install will therefore be to move all client\result_*
Of course, since others is also using your queue, you can't just delete all result_* to remove the bad, but most of the bad is limited to a fairly short upload-interwall so should be after eachother alphabetically.
Note, since *.ini is updated then tried to upload & got the doublet-error, you can't just sort them by time.

Oh, and there are no special naming or sub-dividing in sub-directories of result_* so the only way to know who has uploaded this result is to look on user_id=1234567 inside the file...
Smoke's idea of disallowing new users is a great idea, and hopefully it work as it should. As for manually deleting any of the user.1234567-directories manually isn't necessary, since "Tools/Delete a client" is much easier method.
Looking on the queue, there are currently 5 dropped doublets, so therefore 10 files in client\duplicats.
Problems results queued is upto 482, if not completely mistaken this will increase till all 1349 and then will re-try all the doublets... I don't remember if it's 2nd or 3rd time they will be dropped, so... From the look of the speed most likely Berkeley will accept some of them on 2nd pass-through...