I imported 24 accounts with a 'clone' option from a csv file and got 24 added, 0 updated and 0 skipped.  Inspection of the results showed 2 were cloned.  After inspecting the field contents, I decided that import with overwrite was the better option for me. 

 

So I undid the import succesfully then repeated the test, taking 'overwrite' option instead.  This time I got 22 added and 2 skipped and 0 updated.  Inspection showed the results were matching - ie the test had failed to update the old records with imported record field contents.

 

What am I doing wrong?