Revert "Delete duplicates from collection before completion"

This reverts commit 1b74a85fe6420e02b92a309bdd049f12241aacc0.

The call to delete-dups resulted in significant performance
defradation on large collections.
Remove unnecessary uses of "delete-dups"

"delete-dups" is slow for large collections.
Add underscore to unused variable
Version 2.4