>I've seen this when the key column was not specified in SQL Server as the Primary key.
>
I found a solution. The dedup program is a session based class and it replicated some of our generic procedures as methods of the class (not sure why this was done).

Anyway, in the dedup program version we excluded identity field from the list of updatable fields. In the main program version we didn't exclude it, but had this property
cursorsetprop('AutoIncError',.F.) && ignore error message when updating identity field set for identity field.

I suspect I already dealt with this problem in the past and added that code, but totally forgot about it. Anyway, changing the class method to be the same as our main program method resolved this problem.