a preview of collector collector

So I have not yet completed an algorithm to search for the illusive
singleton in a collector collector --- but I have faith that it will
appear on the horizon --- Simply what I am trying to do is search
a succession of collectors --- ( 1.first elimate uniques til none found )
then eliminate the uniques - go back to  ) - find singletons - by searching
through each collector beginning with first value in first collector - and searching
for a duplicate - in another collector.