Fix EffSort clobbering duplicate inputs #7928
                
     Merged
            
            
          
      
        
          +21
        
        
          −20
        
        
          
        
      
    
  
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Problem
See #7926. Sorting a list with 2 of the same value would result in a sorted list with only 1 of that value instead of 2.
Solution
This was due to using a map to tie current and mapped values, which only allowed a single current value. The solution was to move to a List of paired values, which allows as many duplicated as desired.
Testing Completed
Added a regression test.
Supporting Information
Completes: #7926
Related: none