The original entry was a single individual with very little information and no discoverable duplicate entries. As I added information and each time I corrected the entry, as many as five or more duplicate entries would appear. The screenshot shows less than half of the list of changes that had to be made because of the duplicates that appeared each time information was added. Many of the merges produced even more occurrences of duplicates that had to be merged. I estimate that I had to resolve more than a hundred duplicates to clean up this one family.
I can speculate about what is happening. It appears from consulting with others who are experiencing the same issues, that FamilySearch has added a significant number of additional individuals to the database. Perhaps this comes about as a result of opening up more links to the original data in moving away from the new.FamilySearch.org program? In one case, a duplicate record appeared that could only have been added by the user many years ago.
There are some important issues here. One is that an entry that appears to be without any duplicates, could have many duplicates if some additional research is done and information added. So, for example you find a relative where the entry shows Temple work needed but there is very limited information available. If you do some very basic research, such as adding a birthplace or date or adding a spouse, the Family Tree program will immediately begin finding duplicates that were previously not discoverable. As more information is added, duplicates will continue to appear.
In one case, we assumed that this phenomena was caused by having huge IOUS or multiply submitted entries. However, I have seen instances where duplicates start appearing in lines where there has been very little research and a very limited number of submissions.
What is the solution? Keep carefully merging entries until the duplicates run out. There is apparently no other solution. It is significant that these duplicates have now begun to appear. They have been in the program all along but not found when searching. Now they are being found. This must mean we are closer to separating new.FamilySearch.org and the end of the ultimate problems with the data may be in sight.